##
##
##
+source "ubuntu/compcache/Kconfig"
+##
+##
+##
##
##
##
##
##
##
+obj-$(CONFIG_BLK_DEV_COMPCACHE) += compcache/
+##
+##
+##
##
##
##
--- /dev/null
+Downloaded from: http://code.google.com/p/compcache/
+Current Version: 0.5.3
--- /dev/null
+version 0.5.3 (8/4/2009)
+ - Major cleanups.
+ - Rename module: compcache.ko -> ramzswap.ko
+ - Rename params: backing_dev -> backing_swap
+ - Updated use_compcache.sh script with detailed
+ documentation on parameters.
+ - LZO de/compress modules are no longer packaged
+ with compcache. Most distros now include these.
+
+version 0.5.2 (11/3/2009)
+ - Can forward incompressible pages to physical swap disk.
+ - New module params:
+ - memlimit_kb
+ - disksize_kb
+ - backing_dev
+ See use_compcache.sh for documentation on these params.
+ - Modified use_compcache.sh script to handle new params.
+ - Detect zero-filled pages and don't allocate any memory
+ for them.
+
+version 0.5.1 (22/1/2009)
+ - Fix crash on x86 systems with higmem (mem > ~1G).
+ This required minor changes to atomic (un)map functions (see Issue #20).
+
+version 0.5 (16/1/2009)
+ - Fix crash in case compcache init fails.
+
+version 0.5pre4 (10/1/2009)
+ - Support discarding pages for freed swap blocks (requires 2.6.28-git14).
+ This feature will be disabled if compiled for older kernel.
+ - Mark ramzswap as "solid-state" block device (requires 2.6.26-git14).
+ - Fixed incorrect stats reporting in /proc/compcache (some
+ new stats added too).
+
+version 0.5pre3 (5/1/2009)
+ - Use kmap_atomic() in xvMalloc. This fixes issue #19
+ - Remove xvMapPage() and xvUnmapMap() from xvMalloc.
+
+version 0.5pre2 (28/10/2008)
+ - Alloc full page for uncompressible pages instead
+ of returning I/O error.
+ - Warn users when using ramzswap > (2 x RAM size)
+
+version 0.5pre1 (15/10/2008)
+ - Replaced TLSF with xvMalloc memory allocator
+ http://code.google.com/p/compcache/wiki/xvMalloc
+
+version 0.4 (13/8/2008)
+ - Enable debug and stats option for compcache and tlsf by default
+ proc nodes: /proc/{tlsfinfo,compcache}
+ - Fix crash when reading /proc/tlsfinfo
+ - Lots of cleanups: clean compile on x64
+
+version 0.3 (17/3/2008)
+ - Fix spurious swap read failures
+ - Better swap request filtering
+ - Swap device again renamed to /dev/ramzswap0
+ This is to prevent Ubuntu installer from presenting
+ this device as possible installation target (see Issue #5)
+ - use_compcache.sh script now waits for disk node to be created
+ instead of arbitrary sleep (see Issue #6).
+ - Modified scripts: use_compcache.sh and unuse_compcache.sh
+ to now use new device name (compcache0 -> ramzswap0).
+
+version 0.2 (3/3/2008)
+ - Fixed bug on systems with highmem
+ - Better filtering-out of non-swap requests
+ - Export statistics through proc nodes:
+ - /proc/compcache
+ - /proc/tlsfinfo
+ - Debug and Statistics support for allocator
+ and compcache can now be individually turned
+ on/off by setting DEBUG, STATS to 0/1 in
+ respective header files
+ - Swap device now renamed to /dev/compcache0
+ - Added scripts: use_compcache.sh and unuse_compcache.sh
+ See README for usage
+ - Default compcache size set to 25% of RAM
+ - Lots of code cleanups
+ - Updated README
+ - Created Changelog :)
+
--- /dev/null
+ GNU GENERAL PUBLIC LICENSE
+ Version 2, June 1991
+
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+ END OF TERMS AND CONDITIONS
--- /dev/null
+menu "Compcache options"
+
+config BLK_DEV_COMPCACHE
+ tristate "Compressed RAM based swap device"
+ default m
+ select LZO_COMPRESS
+ select LZO_DECOMPRESS
+ depends on BLOCK
+ help
+ This creates RAM based block device which acts as swap disk. Pages
+ swapped to this disk are compressed and stored in memory itself.
+ Project Home: http://code.google.com/p/compcache/
+
+config BLK_DEV_COMPCACHE_DEBUG
+ default n
+ depends on BLK_DEV_COMPCACHE
+ bool "Enable debugging"
+ help
+ This causes negligible performance loss and size increase.
+ If unsure, say Y.
+
+config BLK_DEV_COMPCACHE_STATS
+ default n
+ depends on BLK_DEV_COMPCACHE
+ bool "Enable statistics"
+ help
+ Creates /proc/compcache to export various statistics.
+ This adds about 4K to size with negligible performance loss.
+ If unsure, say Y.
+
+endmenu
--- /dev/null
+
+ GNU LESSER GENERAL PUBLIC LICENSE
+ Version 2.1, February 1999
+
+ Copyright (C) 1991, 1999 Free Software Foundation, Inc.
+ 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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+ of this license document, but changing it is not allowed.
+
+[This is the first released version of the Lesser GPL. It also counts
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+ the version number 2.1.]
+
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+freedom to share and change it. By contrast, the GNU General Public
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+ Ty Coon, President of Vice
+
+That's all there is to it!
+
+
--- /dev/null
+obj-$(CONFIG_BLK_DEV_COMPCACHE) := ramzswap.o xvmalloc.o
--- /dev/null
+ramzswap: Compressed RAM based swap device
+-------------------------------------------
+
+Project home: http://compcache.googlecode.com
+
+* Introduction
+This is a RAM based block device which acts as swap disk.
+Pages swapped to this device are compressed and stored in
+memory itself. See project home for use cases, performance
+numbers and lot more.
+
+* Compiling
+ - Run 'make': this will compile all modules against your kernel.
+
+ - Following kernel modules are created:
+ - xvmalloc.ko
+ - ramzswap.ko
+
+* Using
+ - Following scipts are included
+ - use_ramzswap.sh [<disksize(KB)|<memlimit(KB)>] [<backing_swap>]
+ This loads all required modules and sets up swap device.
+ NOTE: script contains detailed documentation on parameters.
+
+ - unuse_ramzswap.sh
+ Unloads all modules and turns off ramzswap swap device.
+
+* Common Problems
+ - If you get lots of compile errors, make sure you have package for
+ kernel source installed. For e.g., on Fedora its 'kernel-devel' package.
+
+ - If (un)use_ramzswap scripts fail to work, refer to wiki:
+ http://code.google.com/p/compcache/wiki/CompilingAndUsing
+
+* Notes
+ - Statistics are exported via /proc/ramzswap
+
+Please consider using Issue Tracker:
+http://code.google.com/p/compcache/issues/list
+for reporting any bugs/feature requests.
+
+Cheers!
+Nitin Gupta
+EMail: ngupta at vflare dot org
+
--- /dev/null
+#ifndef _CCACHE_COMPAT_H_
+#define _CCACHE_COMPAT_H_
+
+#include <linux/version.h>
+
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
+#define BIO_IO_ERROR(bio) bio_io_error(bio, PAGE_SIZE)
+#define BIO_ENDIO(bio, error) bio_endio(bio, PAGE_SIZE, error)
+#else
+#define BIO_IO_ERROR(bio) bio_io_error(bio)
+#define BIO_ENDIO(bio, error) bio_endio(bio, error)
+#endif
+
+#ifndef pr_err
+#define pr_err(fmt, arg...) \
+ printk(KERN_ERR fmt, ##arg)
+#endif
+
+#ifndef pr_warning
+#define pr_warning(fmt, arg...) \
+ printk(KERN_WARNING fmt, ##arg)
+#endif
+
+#ifndef pr_info
+#define pr_info(fmt, arg...) \
+ printk(KERN_ERR fmt, ##arg)
+#endif
+
+#ifdef bio_discard
+#define SWAP_DISCARD_SUPPORTED
+#endif
+
+#endif
+
--- /dev/null
+/*
+ * Compressed RAM based swap device
+ *
+ * Copyright (C) 2008, 2009 Nitin Gupta
+ *
+ * This RAM based block device acts as swap disk.
+ * Pages swapped to this device are compressed and
+ * stored in memory.
+ *
+ * Released under the terms of GNU General Public License Version 2.0
+ *
+ * Project home: http://compcache.googlecode.com
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/bitops.h>
+#include <linux/blkdev.h>
+#include <linux/buffer_head.h>
+#include <linux/device.h>
+#include <linux/genhd.h>
+#include <linux/highmem.h>
+#include <linux/lzo.h>
+#include <linux/mutex.h>
+#include <linux/proc_fs.h>
+#include <linux/string.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/vmalloc.h>
+
+#include "compat.h"
+#include "ramzswap.h"
+
+/* Globals */
+static struct ramzswap rzs;
+static struct ramzswap_stats stats;
+/*
+ * Pages that compress to larger than this size are
+ * forwarded to backing swap, if present or stored
+ * uncompressed in memory otherwise.
+ */
+static unsigned int MAX_CPAGE_SIZE;
+
+/* Module params (documentation at end) */
+static unsigned long disksize_kb;
+static unsigned long memlimit_kb;
+static char *backing_swap;
+
+static int __init ramzswap_init(void);
+static struct block_device_operations ramzswap_devops = {
+ .owner = THIS_MODULE,
+};
+
+static int test_flag(u32 index, enum rzs_pageflags flag)
+{
+ return rzs.table[index].flags & BIT(flag);
+}
+
+static void set_flag(u32 index, enum rzs_pageflags flag)
+{
+ rzs.table[index].flags |= BIT(flag);
+}
+
+static void clear_flag(u32 index, enum rzs_pageflags flag)
+{
+ rzs.table[index].flags &= ~BIT(flag);
+}
+
+static int page_zero_filled(void *ptr)
+{
+ u32 pos;
+ u64 *page;
+
+ page = (u64 *)ptr;
+
+ for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
+ if (page[pos])
+ return 0;
+ }
+
+ return 1;
+}
+
+/*
+ * Given <pagenum, offset> pair, provide a dereferencable pointer.
+ */
+static void *get_ptr_atomic(u32 pagenum, u16 offset, enum km_type type)
+{
+ unsigned char *page;
+
+ page = kmap_atomic(pfn_to_page(pagenum), type);
+ return page + offset;
+}
+
+static void put_ptr_atomic(void *ptr, enum km_type type)
+{
+ kunmap_atomic(ptr, type);
+}
+
+#if defined(STATS)
+static struct proc_dir_entry *proc;
+
+static int proc_ramzswap_read(char *page, char **start, off_t off,
+ int count, int *eof, void *data)
+{
+ int len;
+ size_t succ_writes, mem_used;
+ unsigned int good_compress_perc = 0, no_compress_perc = 0;
+
+ mem_used = xv_get_total_size_bytes(rzs.mem_pool)
+ + (stats.pages_expand << PAGE_SHIFT);
+
+ if (off > 0) {
+ *eof = 1;
+ return 0;
+ }
+
+#define K(x) ((x) >> 10)
+ /* Basic stats */
+ len = sprintf(page,
+ "DiskSize: %8zu kB\n",
+ (size_t)(K(rzs.disksize)));
+
+ if (rzs.backing_swap) {
+ /* This must always be less than ComprDataSize */
+ len += sprintf(page + len,
+ "MemLimit: %8zu kB\n",
+ K(rzs.memlimit));
+ }
+
+ succ_writes = stats.num_writes - stats.failed_writes;
+
+ if (succ_writes && stats.pages_stored) {
+ good_compress_perc = stats.good_compress * 100
+ / stats.pages_stored;
+ no_compress_perc = stats.pages_expand * 100
+ / stats.pages_stored;
+ }
+
+ /* Extended stats */
+ len += sprintf(page + len,
+ "NumReads: %8llu\n"
+ "NumWrites: %8llu\n"
+ "FailedReads: %8llu\n"
+ "FailedWrites: %8llu\n"
+ "InvalidIO: %8llu\n"
+ "PagesDiscard: %8llu\n"
+ "ZeroPages: %8u\n"
+ "GoodCompress: %8u %%\n"
+ "NoCompress: %8u %%\n"
+ "PagesStored: %8u\n"
+ "PagesUsed: %8zu\n"
+ "OrigDataSize: %8zu kB\n"
+ "ComprDataSize: %8zu kB\n"
+ "MemUsedTotal: %8zu kB\n",
+ stats.num_reads,
+ stats.num_writes,
+ stats.failed_reads,
+ stats.failed_writes,
+ stats.invalid_io,
+ stats.pages_discard,
+ stats.pages_zero,
+ good_compress_perc,
+ no_compress_perc,
+ stats.pages_stored,
+ mem_used >> PAGE_SHIFT,
+ (size_t)(K(stats.pages_stored << PAGE_SHIFT)),
+ (size_t)(K(stats.compr_size)),
+ (size_t)(K(mem_used)));
+
+ if (rzs.backing_swap) {
+ /* This must always be less than ComprDataSize */
+ len += sprintf(page + len,
+ "BDevNumReads: %8llu\n"
+ "BDevNumWrites: %8llu\n",
+ stats.bdev_num_reads,
+ stats.bdev_num_writes);
+ }
+
+ return len;
+}
+#endif /* STATS */
+
+/*
+ * Check if value of backing_swap module param is sane.
+ * Claim this device and set ramzswap size equal to
+ * size of this block device.
+ */
+static int setup_backing_swap(void)
+{
+ int error = 0;
+ struct inode *inode;
+ struct file *swap_file;
+ struct address_space *mapping;
+ struct block_device *bdev = NULL;
+
+ if (backing_swap == NULL) {
+ pr_debug(C "backing_swap param not given\n");
+ goto out;
+ }
+
+ pr_info(C "Using backing swap device: %s\n", backing_swap);
+
+ swap_file = filp_open(backing_swap, O_RDWR | O_LARGEFILE, 0);
+ if (IS_ERR(swap_file)) {
+ pr_err(C "Error opening backing device: %s\n", backing_swap);
+ error = -EINVAL;
+ goto out;
+ }
+
+ mapping = swap_file->f_mapping;
+ inode = mapping->host;
+
+ if (S_ISBLK(inode->i_mode)) {
+ bdev = I_BDEV(inode);
+ error = bd_claim(bdev, ramzswap_init);
+ if (error < 0) {
+ bdev = NULL;
+ goto bad_param;
+ }
+ rzs.old_block_size = block_size(bdev);
+ error = set_blocksize(bdev, PAGE_SIZE);
+ if (error < 0)
+ goto bad_param;
+ } else {
+ /* TODO: support for regular file as backing swap */
+ pr_info(C "%s is not a block device.\n", backing_swap);
+ error = -EINVAL;
+ goto out;
+ }
+
+ rzs.swap_file = swap_file;
+ rzs.backing_swap = bdev;
+ rzs.disksize = i_size_read(inode);
+ BUG_ON(!rzs.disksize);
+
+ return 0;
+
+bad_param:
+ if (bdev) {
+ set_blocksize(bdev, rzs.old_block_size);
+ bd_release(bdev);
+ }
+ filp_close(swap_file, NULL);
+
+out:
+ rzs.backing_swap = NULL;
+ return error;
+}
+
+/*
+ * Check if request is within bounds and page aligned.
+ */
+static inline int valid_swap_request(struct bio *bio)
+{
+ if (unlikely(
+ (bio->bi_sector >= (rzs.disksize >> SECTOR_SHIFT)) ||
+ (bio->bi_sector & (SECTORS_PER_PAGE - 1)) ||
+ (bio->bi_vcnt != 1) ||
+ (bio->bi_size != PAGE_SIZE) ||
+ (bio->bi_io_vec[0].bv_offset != 0))) {
+
+ return 0;
+ }
+
+ /* swap request is valid */
+ return 1;
+}
+
+static void ramzswap_free_page(size_t index)
+{
+ u32 clen;
+ void *obj;
+
+ u32 pagenum = rzs.table[index].pagenum;
+ u32 offset = rzs.table[index].offset;
+
+ if (unlikely(test_flag(index, RZS_UNCOMPRESSED))) {
+ clen = PAGE_SIZE;
+ __free_page(pfn_to_page(pagenum));
+ clear_flag(index, RZS_UNCOMPRESSED);
+ stat_dec(stats.pages_expand);
+ goto out;
+ }
+
+ obj = get_ptr_atomic(pagenum, offset, KM_USER0);
+ clen = xv_get_object_size(obj) - sizeof(struct zobj_header);
+ put_ptr_atomic(obj, KM_USER0);
+
+ xv_free(rzs.mem_pool, pagenum, offset);
+ stat_dec_if_less(stats.good_compress, clen, PAGE_SIZE / 2 + 1);
+
+out:
+ stats.compr_size -= clen;
+ stat_dec(stats.pages_stored);
+
+ rzs.table[index].pagenum = 0;
+ rzs.table[index].offset = 0;
+}
+
+#ifdef SWAP_DISCARD_SUPPORTED
+static int ramzswap_prepare_discard(struct request_queue *q,
+ struct request *req)
+{
+ return 0;
+}
+
+/*
+ * Called by main I/O handler function. This helper
+ * function handles 'discard' I/O requests which means
+ * that some swap pages are no longer required, so
+ * swap device can take needed action -- we free memory
+ * allocated for these pages.
+ */
+static int ramzswap_discard(struct bio *bio)
+{
+ size_t index, start_page, num_pages;
+
+ start_page = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
+ num_pages = bio->bi_size >> (SECTOR_SHIFT + SECTORS_PER_PAGE_SHIFT);
+
+ for (index = start_page; index < start_page + num_pages; index++) {
+ if (rzs.table[index].pagenum) {
+ ramzswap_free_page(index);
+ stat_inc(stats.pages_discard);
+ }
+ }
+
+ set_bit(BIO_UPTODATE, &bio->bi_flags);
+ BIO_ENDIO(bio, 0);
+ return 0;
+}
+#endif
+
+int handle_zero_page(struct bio *bio)
+{
+ void *user_mem;
+ struct page *page = bio->bi_io_vec[0].bv_page;
+
+ user_mem = get_ptr_atomic(page_to_pfn(page), 0, KM_USER0);
+ memset(user_mem, 0, PAGE_SIZE);
+ put_ptr_atomic(user_mem, KM_USER0);
+
+ set_bit(BIO_UPTODATE, &bio->bi_flags);
+ BIO_ENDIO(bio, 0);
+ return 0;
+}
+
+int handle_uncompressed_page(struct bio *bio)
+{
+ u32 index;
+ struct page *page;
+ unsigned char *user_mem, *cmem;
+
+ page = bio->bi_io_vec[0].bv_page;
+ index = bio->bi_sector >>SECTORS_PER_PAGE_SHIFT;
+
+ user_mem = get_ptr_atomic(page_to_pfn(page), 0, KM_USER0);
+ cmem = get_ptr_atomic(rzs.table[index].pagenum,
+ rzs.table[index].offset, KM_USER1);
+
+ memcpy(user_mem, cmem, PAGE_SIZE);
+ put_ptr_atomic(user_mem, KM_USER0);
+ put_ptr_atomic(cmem, KM_USER1);
+
+ set_bit(BIO_UPTODATE, &bio->bi_flags);
+ BIO_ENDIO(bio, 0);
+ return 0;
+}
+
+
+/*
+ * Called when request page is not present in ramzswap.
+ * Its either in backing swap device (if present) or
+ * this is an attempt to read before any previous write
+ * to this location - this happens due to readahead when
+ * swap device is read from user-space (e.g. during swapon)
+ */
+int handle_ramzswap_fault(struct bio *bio)
+{
+ void *user_mem;
+ struct page *page = bio->bi_io_vec[0].bv_page;
+
+ /*
+ * Always forward such requests to backing swap
+ * device (if present)
+ */
+ if (rzs.backing_swap) {
+ stat_dec(stats.num_reads);
+ stat_inc(stats.bdev_num_reads);
+ bio->bi_bdev = rzs.backing_swap;
+ return 1;
+ }
+
+ /*
+ * Its unlikely event in case backing dev is
+ * not present
+ */
+ pr_debug(C "Read before write on swap device: "
+ "sector=%lu, size=%u, offset=%u\n",
+ (ulong)(bio->bi_sector), bio->bi_size,
+ bio->bi_io_vec[0].bv_offset);
+ user_mem = kmap(page);
+ memset(user_mem, 0, PAGE_SIZE);
+ kunmap(page);
+
+ set_bit(BIO_UPTODATE, &bio->bi_flags);
+ BIO_ENDIO(bio, 0);
+ return 0;
+}
+
+int ramzswap_read(struct bio *bio)
+{
+ int ret;
+ u32 index;
+ size_t clen;
+ struct page *page;
+ struct zobj_header *zheader;
+ unsigned char *user_mem, *cmem;
+
+ stat_inc(stats.num_reads);
+
+ page = bio->bi_io_vec[0].bv_page;
+ index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
+
+ if (test_flag(index, RZS_ZERO))
+ return handle_zero_page(bio);
+
+ /* Requested page is not present in compressed area */
+ if (!rzs.table[index].pagenum)
+ return handle_ramzswap_fault(bio);
+
+ /* Page is stored uncompressed since its incompressible */
+ if (unlikely(test_flag(index, RZS_UNCOMPRESSED)))
+ return handle_uncompressed_page(bio);
+
+ user_mem = get_ptr_atomic(page_to_pfn(page), 0, KM_USER0);
+ clen = PAGE_SIZE;
+
+ cmem = get_ptr_atomic(rzs.table[index].pagenum,
+ rzs.table[index].offset, KM_USER1);
+
+ ret = lzo1x_decompress_safe(
+ cmem + sizeof(*zheader),
+ xv_get_object_size(cmem) - sizeof(*zheader),
+ user_mem, &clen);
+
+ put_ptr_atomic(user_mem, KM_USER0);
+ put_ptr_atomic(cmem, KM_USER1);
+
+ /* should NEVER happen */
+ if (unlikely(ret != LZO_E_OK)) {
+ pr_err(C "Decompression failed! err=%d, page=%u\n",
+ ret, index);
+ stat_inc(stats.failed_reads);
+ goto out;
+ }
+
+ set_bit(BIO_UPTODATE, &bio->bi_flags);
+ BIO_ENDIO(bio, 0);
+ return 0;
+
+out:
+ BIO_IO_ERROR(bio);
+ return 0;
+}
+
+int ramzswap_write(struct bio *bio)
+{
+ int ret, fwd_write_request = 0;
+ u32 offset;
+ size_t clen, index;
+ struct zobj_header *zheader;
+ struct page *page, *page_store;
+ unsigned char *user_mem, *cmem, *src;
+
+ stat_inc(stats.num_writes);
+
+ page = bio->bi_io_vec[0].bv_page;
+ index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
+
+ src = rzs.compress_buffer;
+
+ /*
+ * System swaps to same sector again when the stored page
+ * is no longer referenced by any process. So, its now safe
+ * to free the memory that was allocated for this page.
+ */
+ if (rzs.table[index].pagenum)
+ ramzswap_free_page(index);
+
+ /*
+ * No memory ia allocated for zero filled pages.
+ * Simply clear zero page flag.
+ */
+ if (test_flag(index, RZS_ZERO)) {
+ stat_dec(stats.pages_zero);
+ clear_flag(index, RZS_ZERO);
+ }
+
+ mutex_lock(&rzs.lock);
+
+ user_mem = get_ptr_atomic(page_to_pfn(page), 0, KM_USER0);
+ if (page_zero_filled(user_mem)) {
+ put_ptr_atomic(user_mem, KM_USER0);
+ mutex_unlock(&rzs.lock);
+ stat_inc(stats.pages_zero);
+ set_flag(index, RZS_ZERO);
+
+ set_bit(BIO_UPTODATE, &bio->bi_flags);
+ BIO_ENDIO(bio, 0);
+ return 0;
+ }
+
+ if (rzs.backing_swap &&
+ (stats.compr_size > rzs.memlimit - PAGE_SIZE)) {
+ put_ptr_atomic(user_mem, KM_USER0);
+ mutex_unlock(&rzs.lock);
+ fwd_write_request = 1;
+ goto out;
+ }
+
+ ret = lzo1x_1_compress(user_mem, PAGE_SIZE, src, &clen,
+ rzs.compress_workmem);
+
+ put_ptr_atomic(user_mem, KM_USER0);
+
+ if (unlikely(ret != LZO_E_OK)) {
+ mutex_unlock(&rzs.lock);
+ pr_err(C "Compression failed! err=%d\n", ret);
+ stat_inc(stats.failed_writes);
+ goto out;
+ }
+
+ /*
+ * Page is incompressible. Forward it to backing swap
+ * if present. Otherwise, store it as-is (uncompressed)
+ * since we do not want to return too many swap write
+ * errors which has side effect of hanging the system.
+ */
+ if (unlikely(clen > MAX_CPAGE_SIZE)) {
+ if (rzs.backing_swap) {
+ mutex_unlock(&rzs.lock);
+ fwd_write_request = 1;
+ goto out;
+ }
+
+ clen = PAGE_SIZE;
+ page_store = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
+ if (unlikely(!page_store)) {
+ mutex_unlock(&rzs.lock);
+ stat_inc(stats.failed_writes);
+ goto out;
+ }
+
+ offset = 0;
+ set_flag(index, RZS_UNCOMPRESSED);
+ stat_inc(stats.pages_expand);
+ rzs.table[index].pagenum = page_to_pfn(page_store);
+ src = get_ptr_atomic(page_to_pfn(page), 0, KM_USER0);
+ goto memstore;
+ }
+
+ if (xv_malloc(rzs.mem_pool, clen + sizeof(*zheader),
+ &rzs.table[index].pagenum, &offset,
+ GFP_NOIO | __GFP_HIGHMEM)) {
+ mutex_unlock(&rzs.lock);
+ pr_info(C "Error allocating memory for compressed "
+ "page: %zu, size=%zu\n", index, clen);
+ stat_inc(stats.failed_writes);
+ if (rzs.backing_swap)
+ fwd_write_request = 1;
+ goto out;
+ }
+
+memstore:
+ rzs.table[index].offset = offset;
+
+ cmem = get_ptr_atomic(rzs.table[index].pagenum,
+ rzs.table[index].offset, KM_USER1);
+
+#if 0
+ /* Back-reference needed for memory defragmentation */
+ if (!test_flag(index, RZS_UNCOMPRESSED)) {
+ zheader = (struct zobj_header *)cmem;
+ zheader->table_idx = index;
+ cmem += sizeof(*zheader);
+ }
+#endif
+
+ memcpy(cmem, src, clen);
+
+ put_ptr_atomic(cmem, KM_USER1);
+ if (unlikely(test_flag(index, RZS_UNCOMPRESSED)))
+ put_ptr_atomic(src, KM_USER0);
+
+ /* Update stats */
+ stats.compr_size += clen;
+ stat_inc(stats.pages_stored);
+ stat_inc_if_less(stats.good_compress, clen, PAGE_SIZE / 2 + 1);
+
+ mutex_unlock(&rzs.lock);
+
+ set_bit(BIO_UPTODATE, &bio->bi_flags);
+ BIO_ENDIO(bio, 0);
+ return 0;
+
+out:
+ if (fwd_write_request) {
+ stat_inc(stats.bdev_num_writes);
+ bio->bi_bdev = rzs.backing_swap;
+ return 1;
+ }
+
+ BIO_IO_ERROR(bio);
+ return 0;
+}
+
+/*
+ * Handler function for all ramzswap I/O requests.
+ */
+static int ramzswap_make_request(struct request_queue *queue, struct bio *bio)
+{
+ int ret = 0;
+
+#ifdef SWAP_DISCARD_SUPPORTED
+ if (bio_discard(bio))
+ return ramzswap_discard(bio);
+#endif
+
+ if (!valid_swap_request(bio)) {
+ stat_inc(stats.invalid_io);
+ BIO_IO_ERROR(bio);
+ return 0;
+ }
+
+ switch (bio_data_dir(bio)) {
+ case READ:
+ ret = ramzswap_read(bio);
+ break;
+
+ case WRITE:
+ ret = ramzswap_write(bio);
+ break;
+ }
+
+ return ret;
+}
+
+/*
+ * Swap header (1st page of swap device) contains information
+ * to indentify it as a swap partition. Prepare such a header
+ * for ramzswap device (ramzswap0) so that swapon can identify
+ * it as swap partition. In case backing swap device is provided,
+ * copy its swap header.
+ */
+static int setup_swap_header(union swap_header *s)
+{
+ int ret = 0;
+ struct page *page;
+ struct address_space *mapping;
+ union swap_header *backing_swap_header;
+
+ /*
+ * There is no backing swap device. Create a swap header
+ * that is acceptable by swapon.
+ */
+ if (rzs.backing_swap == NULL) {
+ s->info.version = 1;
+ s->info.last_page = rzs.disksize >> PAGE_SHIFT;
+ s->info.nr_badpages = 0;
+ memcpy(s->magic.magic, "SWAPSPACE2", 10);
+ return 0;
+ }
+
+ /*
+ * We have a backing swap device. Copy its swap header
+ * to ramzswap device header. If this header contains
+ * invalid information (backing device not a swap
+ * partition, etc.), swapon will fail for ramzswap
+ * which is correct behavior - we don't want to swap
+ * over filesystem partition!
+ */
+
+ /* Read the backing swap header (code from sys_swapon) */
+ mapping = rzs.swap_file->f_mapping;
+ if (!mapping->a_ops->readpage) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ page = read_mapping_page(mapping, 0, rzs.swap_file);
+ if (IS_ERR(page)) {
+ ret = PTR_ERR(page);
+ goto out;
+ }
+
+ backing_swap_header = kmap(page);
+ *s = *backing_swap_header;
+ kunmap(page);
+
+out:
+ return ret;
+}
+
+static void ramzswap_set_disksize(size_t totalram_bytes)
+{
+ rzs.disksize = disksize_kb << 10;
+
+ if (!disksize_kb) {
+ pr_info(C
+ "disk size not provided. You can use disksize_kb module "
+ "param to specify size.\nUsing default: (%u%% of RAM).\n",
+ DEFAULT_DISKSIZE_PERC_RAM
+ );
+ rzs.disksize = DEFAULT_DISKSIZE_PERC_RAM *
+ (totalram_bytes / 100);
+ }
+
+ if (disksize_kb > 2 * (totalram_bytes >> 10)) {
+ pr_info(C
+ "There is little point creating a ramzswap of greater than "
+ "twice the size of memory since we expect a 2:1 compression "
+ "ratio. Note that ramzswap uses about 0.1%% of the size of "
+ "the swap device when not in use so a huge ramzswap is "
+ "wasteful.\n"
+ "\tMemory Size: %zu kB\n"
+ "\tSize you selected: %lu kB\n"
+ "Continuing anyway ...\n",
+ totalram_bytes >> 10, disksize_kb
+ );
+ }
+
+ rzs.disksize &= PAGE_MASK;
+ pr_info(C "disk size set to %zu kB\n", rzs.disksize >> 10);
+}
+
+/*
+ * memlimit cannot be greater than backing disk size.
+ */
+static void ramzswap_set_memlimit(size_t totalram_bytes)
+{
+ int memlimit_valid = 1;
+ rzs.memlimit = memlimit_kb << 10;
+
+ if (!rzs.memlimit) {
+ pr_info(C "memory limit not set. You can use "
+ "memlimit_kb module param to specify limit.");
+ memlimit_valid = 0;
+ }
+
+ if (rzs.memlimit > rzs.disksize) {
+ pr_info(C "memory limit cannot be greater than "
+ "disksize: limit=%zu, disksize=%zu",
+ rzs.memlimit, rzs.disksize);
+ memlimit_valid = 0;
+ }
+
+ if (!memlimit_valid) {
+ size_t mempart, disksize;
+ pr_info(C "\nUsing default: MIN[(%u%% of RAM), "
+ "(backing disk size)].\n",
+ DEFAULT_MEMLIMIT_PERC_RAM);
+ mempart = DEFAULT_MEMLIMIT_PERC_RAM * (totalram_bytes / 100);
+ disksize = rzs.disksize;
+ rzs.memlimit = mempart > disksize ? disksize : mempart;
+ }
+
+ if (rzs.memlimit > totalram_bytes / 2) {
+ pr_info(C
+ "Its not advisable setting limit more than half of "
+ "size of memory since we expect a 2:1 compression ratio. "
+ "Limit represents amount of *compressed* data we can keep "
+ "in memory!\n"
+ "\tMemory Size: %zu kB\n"
+ "\tLimit you selected: %lu kB\n"
+ "Continuing anyway ...\n",
+ totalram_bytes >> 10, memlimit_kb
+ );
+ }
+
+ rzs.memlimit &= PAGE_MASK;
+ BUG_ON(!rzs.memlimit);
+
+ pr_info(C "memory limit set to %zu kB\n", rzs.memlimit >> 10);
+}
+
+static int __init ramzswap_init(void)
+{
+ int ret;
+ size_t num_pages, totalram_bytes;
+ struct sysinfo i;
+ struct page *page;
+ void *swap_header;
+
+ mutex_init(&rzs.lock);
+
+ ret = setup_backing_swap();
+ if (ret)
+ goto fail;
+
+ si_meminfo(&i);
+ /* Here is a trivia: guess unit used for i.totalram !! */
+ totalram_bytes = i.totalram << PAGE_SHIFT;
+
+ if (rzs.backing_swap)
+ ramzswap_set_memlimit(totalram_bytes);
+ else
+ ramzswap_set_disksize(totalram_bytes);
+
+ rzs.compress_workmem = kmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
+ if (rzs.compress_workmem == NULL) {
+ pr_err(C "Error allocating compressor working memory\n");
+ ret = -ENOMEM;
+ goto fail;
+ }
+
+ rzs.compress_buffer = kmalloc(2 * PAGE_SIZE, GFP_KERNEL);
+ if (rzs.compress_buffer == NULL) {
+ pr_err(C "Error allocating compressor buffer space\n");
+ ret = -ENOMEM;
+ goto fail;
+ }
+
+ num_pages = rzs.disksize >> PAGE_SHIFT;
+ rzs.table = vmalloc(num_pages * sizeof(*rzs.table));
+ if (rzs.table == NULL) {
+ pr_err(C "Error allocating ramzswap address table\n");
+ ret = -ENOMEM;
+ goto fail;
+ }
+ memset(rzs.table, 0, num_pages * sizeof(*rzs.table));
+
+ page = alloc_page(__GFP_ZERO);
+ if (page == NULL) {
+ pr_err(C "Error allocating swap header page\n");
+ ret = -ENOMEM;
+ goto fail;
+ }
+ rzs.table[0].pagenum = page_to_pfn(page);
+ set_flag(0, RZS_UNCOMPRESSED);
+
+ swap_header = kmap(page);
+ ret = setup_swap_header((union swap_header *)(swap_header));
+ kunmap(page);
+ if (ret) {
+ pr_err(C "Error setting swap header\n");
+ goto fail;
+ }
+
+ rzs.disk = alloc_disk(1);
+ if (rzs.disk == NULL) {
+ pr_err(C "Error allocating disk structure\n");
+ ret = -ENOMEM;
+ goto fail;
+ }
+
+ rzs.disk->first_minor = 0;
+ rzs.disk->fops = &ramzswap_devops;
+ /*
+ * It is named like this to prevent distro installers
+ * from offering ramzswap as installation target. They
+ * seem to ignore all devices beginning with 'ram'
+ */
+ strcpy(rzs.disk->disk_name, "ramzswap0");
+
+ rzs.disk->major = register_blkdev(0, rzs.disk->disk_name);
+ if (rzs.disk->major < 0) {
+ pr_err(C "Cannot register block device\n");
+ ret = -EFAULT;
+ goto fail;
+ }
+
+ rzs.disk->queue = blk_alloc_queue(GFP_KERNEL);
+ if (rzs.disk->queue == NULL) {
+ pr_err(C "Cannot register disk queue\n");
+ ret = -EFAULT;
+ goto fail;
+ }
+
+ set_capacity(rzs.disk, rzs.disksize >> SECTOR_SHIFT);
+ blk_queue_make_request(rzs.disk->queue, ramzswap_make_request);
+
+#ifdef QUEUE_FLAG_NONROT
+ /*
+ * Assuming backing device is "rotational" type.
+ * TODO: check if its actually "non-rotational" (SSD).
+ *
+ * We have ident mapping of sectors for ramzswap and
+ * and the backing swap device. So, this queue flag
+ * should be according to backing dev.
+ */
+ if (!rzs.backing_swap)
+ queue_flag_set_unlocked(QUEUE_FLAG_NONROT, rzs.disk->queue);
+#endif
+#ifdef SWAP_DISCARD_SUPPORTED
+ blk_queue_set_discard(rzs.disk->queue, ramzswap_prepare_discard);
+#endif
+ blk_queue_logical_block_size(rzs.disk->queue, PAGE_SIZE);
+ add_disk(rzs.disk);
+
+ rzs.mem_pool = xv_create_pool();
+ if (!rzs.mem_pool) {
+ pr_err(C "Error creating memory pool\n");
+ ret = -ENOMEM;
+ goto fail;
+ }
+
+#if defined(STATS)
+ proc = create_proc_entry("ramzswap", S_IRUGO, NULL);
+ if (proc)
+ proc->read_proc = &proc_ramzswap_read;
+ else {
+ ret = -ENOMEM;
+ pr_warning(C "Error creating proc entry\n");
+ goto fail;
+ }
+#endif
+
+ /*
+ * Pages that compress to size greater than this are forwarded
+ * to physical swap disk (if backing dev is provided)
+ */
+ if (rzs.backing_swap)
+ MAX_CPAGE_SIZE = MAX_CPAGE_SIZE_BDEV;
+ else
+ MAX_CPAGE_SIZE = MAX_CPAGE_SIZE_NOBDEV;
+
+ pr_debug(C "Max compressed page size: %u bytes\n", MAX_CPAGE_SIZE);
+
+ pr_debug(C "Initialization done!\n");
+ return 0;
+
+fail:
+ if (rzs.disk != NULL) {
+ if (rzs.disk->major > 0)
+ unregister_blkdev(rzs.disk->major, rzs.disk->disk_name);
+ del_gendisk(rzs.disk);
+ }
+
+ if (rzs.table && rzs.table[0].pagenum)
+ __free_page(pfn_to_page(rzs.table[0].pagenum));
+ kfree(rzs.compress_workmem);
+ kfree(rzs.compress_buffer);
+ vfree(rzs.table);
+ xv_destroy_pool(rzs.mem_pool);
+#if defined(STATS)
+ if (proc)
+ remove_proc_entry("ramzswap", proc->parent);
+#endif
+ pr_err(C "Initialization failed: err=%d\n", ret);
+ return ret;
+}
+
+static void __exit ramzswap_exit(void)
+{
+ size_t index, num_pages;
+ num_pages = rzs.disksize >> PAGE_SHIFT;
+
+ unregister_blkdev(rzs.disk->major, rzs.disk->disk_name);
+ del_gendisk(rzs.disk);
+
+ /* Close backing swap device (if present) */
+ if (rzs.backing_swap) {
+ set_blocksize(rzs.backing_swap, rzs.old_block_size);
+ bd_release(rzs.backing_swap);
+ filp_close(rzs.swap_file, NULL);
+ }
+
+ __free_page(pfn_to_page(rzs.table[0].pagenum));
+ kfree(rzs.compress_workmem);
+ kfree(rzs.compress_buffer);
+
+ /* Free all pages that are still in ramzswap */
+ for (index = 1; index < num_pages; index++) {
+ u32 pagenum, offset;
+
+ pagenum = rzs.table[index].pagenum;
+ offset = rzs.table[index].offset;
+
+ if (!pagenum)
+ continue;
+
+ if (unlikely(test_flag(index, RZS_UNCOMPRESSED)))
+ __free_page(pfn_to_page(pagenum));
+ else
+ xv_free(rzs.mem_pool, pagenum, offset);
+ }
+
+ vfree(rzs.table);
+ xv_destroy_pool(rzs.mem_pool);
+
+#if defined(STATS)
+ remove_proc_entry("ramzswap", proc->parent);
+#endif
+ pr_debug(C "cleanup done!\n");
+}
+
+/*
+ * This param is applicable only when there is no backing swap device.
+ * We ignore this param in case backing dev is provided since then its
+ * always equal to size of the backing swap device.
+ *
+ * This size refers to amount of (uncompressed) data it can hold.
+ * For e.g. disksize_kb=1024 means it can hold 1024kb worth of
+ * uncompressed data even if this data compresses to just, say, 100kb.
+ *
+ * Default value is used if this param is missing or 0 (if its applicable).
+ * Default: [DEFAULT_DISKSIZE_PERC_RAM]% of RAM
+ */
+module_param(disksize_kb, ulong, 0);
+MODULE_PARM_DESC(disksize_kb, "ramzswap device size (kB)");
+
+/*
+ * This param is applicable only when backing swap device is provided.
+ * This refers to limit on amount of (compressed) data it can hold in
+ * memory. Note that total amount of memory used (MemUsedTotal) can
+ * exceed this memlimit since that includes memory wastage due to
+ * fragmentation and metadata overhead.
+ *
+ * Any additional data beyond this limit is forwarded to backing
+ * swap device. TODO: allow changing memlimit at runtime.
+ *
+ * Default value is used if this param is missing or 0 (if its applicable).
+ * Default: MIN([DEFAULT_MEMLIMIT_PERC_RAM]% of RAM, Backing Device Size)
+ */
+module_param(memlimit_kb, ulong, 0);
+MODULE_PARM_DESC(memlimit_kb, "ramzswap memory limit (kB)");
+
+/*
+ * This is block device to be used as backing store for ramzswap.
+ * When pages more than memlimit_kb as swapped to ramzswap, we store
+ * any additional pages in this device. We may also move some pages
+ * from ramzswap to this device in case system is really low on
+ * memory (TODO).
+ *
+ * This device is not directly visible to kernel as a swap device
+ * (/proc/swaps will only show /dev/ramzswap0 and not this device).
+ * Managing this backing device is the job of ramzswap module.
+ */
+module_param(backing_swap, charp, 0);
+MODULE_PARM_DESC(backing_swap, "Backing swap partition");
+
+module_init(ramzswap_init);
+module_exit(ramzswap_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
+MODULE_DESCRIPTION("Compressed RAM Based Swap Device");
--- /dev/null
+/*
+ * Compressed RAM based swap device
+ *
+ * Copyright (C) 2008, 2009 Nitin Gupta
+ *
+ * This RAM based block device acts as swap disk.
+ * Pages swapped to this device are compressed and
+ * stored in memory.
+ *
+ * Released under the terms of GNU General Public License Version 2.0
+ *
+ * Project home: http://compcache.googlecode.com
+ */
+
+#ifndef _RAMZSWAP_H_
+#define _RAMZSWAP_H_
+
+#include "xvmalloc.h"
+
+/*
+ * Stored at beginning of each compressed object.
+ *
+ * It stores back-reference to table entry which points to this
+ * object. This is required to support memory defragmentation or
+ * migrating compressed pages to backing swap disk.
+ */
+struct zobj_header {
+#if 0
+ u32 table_idx;
+#endif
+};
+
+/*-- Configurable parameters */
+
+/* Default ramzswap disk size: 25% of total RAM */
+#define DEFAULT_DISKSIZE_PERC_RAM 25
+#define DEFAULT_MEMLIMIT_PERC_RAM 15
+
+/*
+ * Max compressed page size when backing device is provided.
+ * Pages that compress to size greater than this are sent to
+ * physical swap disk.
+ */
+#define MAX_CPAGE_SIZE_BDEV (PAGE_SIZE / 2)
+
+/*
+ * Max compressed page size when there is no backing dev.
+ * Pages that compress to size greater than this are stored
+ * uncompressed in memory.
+ */
+#define MAX_CPAGE_SIZE_NOBDEV (PAGE_SIZE / 4 * 3)
+
+/*
+ * NOTE: MAX_CPAGE_SIZE_{BDEV,NOBDEV} sizes must be
+ * less than or equal to:
+ * XV_MAX_ALLOC_SIZE - sizeof(struct zobj_header)
+ * since otherwise xvMalloc would always return failure.
+ */
+
+/*-- End of configurable params */
+
+#define SECTOR_SHIFT 9
+#define SECTOR_SIZE (1 << SECTOR_SHIFT)
+#define SECTORS_PER_PAGE_SHIFT (PAGE_SHIFT - SECTOR_SHIFT)
+#define SECTORS_PER_PAGE (1 << SECTORS_PER_PAGE_SHIFT)
+
+/* Message prefix */
+#define C "ramzswap: "
+
+/* Debugging and Stats */
+#define NOP do { } while (0)
+
+#if defined(CONFIG_BLK_DEV_RAMZSWAP_STATS)
+#define STATS
+#endif
+
+#if defined(STATS)
+#define stat_inc(stat) ((stat)++)
+#define stat_dec(stat) ((stat)--)
+#define stat_inc_if_less(stat, val1, val2) \
+ ((stat) += ((val1) < (val2) ? 1 : 0))
+#define stat_dec_if_less(stat, val1, val2) \
+ ((stat) -= ((val1) < (val2) ? 1 : 0))
+#else /* STATS */
+#define stat_inc(x) NOP
+#define stat_dec(x) NOP
+#define stat_inc_if_less(x, v1, v2) NOP
+#define stat_dec_if_less(x, v1, v2) NOP
+#endif /* STATS */
+
+/* Flags for ramzswap pages (table[page_no].flags) */
+enum rzs_pageflags {
+ /* Page is stored uncompressed */
+ RZS_UNCOMPRESSED,
+
+ /* Page consists entirely of zeros */
+ RZS_ZERO,
+
+ __NR_RZS_PAGEFLAGS,
+};
+
+/*-- Data structures */
+
+/* Indexed by page no. */
+struct table {
+ u32 pagenum;
+ u16 offset;
+ u8 count; /* object ref count (not yet used) */
+ u8 flags;
+};
+
+struct ramzswap {
+ struct xv_pool *mem_pool;
+ void *compress_workmem;
+ void *compress_buffer;
+ struct table *table;
+ struct mutex lock;
+ struct gendisk *disk;
+ /*
+ * This is limit on compressed data size (stats.compr_size)
+ * Its applicable only when backing swap device is present.
+ */
+ size_t memlimit; /* bytes */
+ /*
+ * This is limit on amount of *uncompressed* worth of data
+ * we can hold. When backing swap device is provided, it is
+ * set equal to device size.
+ */
+ size_t disksize; /* bytes */
+
+ /* backing swap device info */
+ struct block_device *backing_swap;
+ struct file *swap_file;
+ int old_block_size;
+};
+
+struct ramzswap_stats {
+ /* basic stats */
+ size_t compr_size; /* compressed size of pages stored -
+ * needed to enforce memlimit */
+ /* more stats */
+#if defined(STATS)
+ u64 num_reads; /* failed + successful */
+ u64 num_writes; /* --do-- */
+ u64 failed_reads; /* can happen when memory is too low */
+ u64 failed_writes; /* should NEVER! happen */
+ u64 invalid_io; /* non-swap I/O requests */
+ u64 pages_discard; /* no. of pages freed by discard callback */
+ u32 pages_zero; /* no. of zero filled pages */
+ u32 pages_stored; /* no. of pages currently stored */
+ u32 good_compress; /* no. of pages with compression ratio<=50% */
+ u32 pages_expand; /* no. of incompressible pages */
+ u64 bdev_num_reads; /* no. of reads on backing dev */
+ u64 bdev_num_writes; /* no. of writes on backing dev */
+#endif
+};
+/*-- */
+
+#endif
--- /dev/null
+/*
+ * xvmalloc.c
+ *
+ * Copyright (C) 2008, 2009 Nitin Gupta
+ *
+ * This code is released using a dual license strategy: GPL/LGPL
+ * You can choose the licence that better fits your requirements.
+ *
+ * Released under the terms of GNU General Public License Version 2.0
+ * Released under the terms of GNU Lesser General Public License Version 2.1
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+
+#include "xvmalloc.h"
+#include "xvmalloc_int.h"
+
+static void stat_inc(u64 *value)
+{
+ *value = *value + 1;
+}
+
+static void stat_dec(u64 *value)
+{
+ *value = *value - 1;
+}
+
+static int test_flag(struct block_header *block, enum blockflags flag)
+{
+ return block->prev & BIT(flag);
+}
+
+static void set_flag(struct block_header *block, enum blockflags flag)
+{
+ block->prev |= BIT(flag);
+}
+
+static void clear_flag(struct block_header *block, enum blockflags flag)
+{
+ block->prev &= ~BIT(flag);
+}
+
+/*
+ * Given <pagenum, offset> pair, provide a derefrencable pointer.
+ * This is called from xv_malloc/xv_free path, so it needs to be fast.
+ */
+static void *get_ptr_atomic(u32 pagenum, u16 offset, enum km_type type)
+{
+ unsigned char *base;
+
+ base = kmap_atomic(pfn_to_page(pagenum), type);
+ return base + offset;
+}
+
+static void put_ptr_atomic(void *ptr, enum km_type type)
+{
+ kunmap_atomic(ptr, type);
+}
+
+static u32 get_blockprev(struct block_header *block)
+{
+ return block->prev & PREV_MASK;
+}
+
+static void set_blockprev(struct block_header *block, u16 new_offset)
+{
+ block->prev = new_offset | (block->prev & FLAGS_MASK);
+}
+
+static struct block_header *BLOCK_NEXT(struct block_header *block)
+{
+ return (struct block_header *)((char *)block + block->size + XV_ALIGN);
+}
+
+/*
+ * Get index of free list containing blocks of maximum size
+ * which is less than or equal to given size.
+ */
+static u32 get_index_for_insert(u32 size)
+{
+ if (unlikely(size > XV_MAX_ALLOC_SIZE))
+ size = XV_MAX_ALLOC_SIZE;
+ size &= ~FL_DELTA_MASK;
+ return (size - XV_MIN_ALLOC_SIZE) >> FL_DELTA_SHIFT;
+}
+
+/*
+ * Get index of free list having blocks of size greater than
+ * or equal to requested size.
+ */
+static u32 get_index(u32 size)
+{
+ if (unlikely(size < XV_MIN_ALLOC_SIZE))
+ size = XV_MIN_ALLOC_SIZE;
+ size = ALIGN(size, FL_DELTA);
+ return (size - XV_MIN_ALLOC_SIZE) >> FL_DELTA_SHIFT;
+}
+
+/*
+ * Allocate a memory page. Called when a pool needs to grow.
+ */
+static u32 xv_alloc_page(gfp_t flags)
+{
+ struct page *page;
+
+ //page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
+ page = alloc_page(flags);
+ if (unlikely(!page))
+ return 0;
+
+ return page_to_pfn(page);
+}
+
+/*
+ * Called when all objects in a page are freed.
+ */
+static void xv_free_page(u32 pagenum)
+{
+ __free_page(pfn_to_page(pagenum));
+}
+
+/**
+ * find_block - find block of at least given size
+ * @pool: memory pool to search from
+ * @size: size of block required
+ * @pagenum: page no. containing required block
+ * @offset: offset within the page where block is located.
+ *
+ * Searches two level bitmap to locate block of at least
+ * the given size. If such a block is found, it provides
+ * <pagenum, offset> to identify this block and returns index
+ * in freelist where we found this block.
+ * Otherwise, returns 0 and <pagenum, offset> params are not touched.
+ */
+static u32 find_block(struct xv_pool *pool, u32 size,
+ u32 *pagenum, u32 *offset)
+{
+ ulong flbitmap, slbitmap;
+ u32 flindex, slindex, slbitstart;
+
+ /* There are no free blocks in this pool */
+ if (!pool->flbitmap)
+ return 0;
+
+ /* Get freelist index correspoding to this size */
+ slindex = get_index(size);
+ slbitmap = pool->slbitmap[slindex / BITS_PER_LONG];
+ slbitstart = slindex % BITS_PER_LONG;
+
+ /*
+ * If freelist is not empty at this index, we found the
+ * block - head of this list. This is approximate best-fit match.
+ */
+ if (test_bit(slbitstart, &slbitmap)) {
+ *pagenum = pool->freelist[slindex].pagenum;
+ *offset = pool->freelist[slindex].offset;
+ return slindex;
+ }
+
+ /*
+ * No best-fit found. Search a bit further in bitmap for a free block.
+ * Second level bitmap consists of series of 32-bit chunks. Search
+ * further in the chunk where we expected a best-fit, starting from
+ * index location found above.
+ */
+ slbitstart++;
+ slbitmap >>= slbitstart;
+
+ /* Skip this search if we were already at end of this bitmap chunk */
+ if ((slbitstart != BITS_PER_LONG) && slbitmap) {
+ slindex += __ffs(slbitmap) + 1;
+ *pagenum = pool->freelist[slindex].pagenum;
+ *offset = pool->freelist[slindex].offset;
+ return slindex;
+ }
+
+ /* Now do a full two-level bitmap search to find next nearest fit */
+ flindex = slindex / BITS_PER_LONG;
+
+ flbitmap = (pool->flbitmap) >> (flindex + 1);
+ if (!flbitmap)
+ return 0;
+
+ flindex += __ffs(flbitmap) + 1;
+ slbitmap = pool->slbitmap[flindex];
+ slindex = (flindex * BITS_PER_LONG) + __ffs(slbitmap);
+ *pagenum = pool->freelist[slindex].pagenum;
+ *offset = pool->freelist[slindex].offset;
+
+ return slindex;
+}
+
+/*
+ * Insert block at <pagenum, offset> in freelist of given pool.
+ * freelist used depends on block size.
+ */
+static void insert_block(struct xv_pool *pool, u32 pagenum, u32 offset,
+ struct block_header *block)
+{
+ u32 flindex, slindex;
+ struct block_header *nextblock;
+
+ slindex = get_index_for_insert(block->size);
+ flindex = slindex / BITS_PER_LONG;
+
+ block->link.prev_pagenum = 0;
+ block->link.prev_offset = 0;
+ block->link.next_pagenum = pool->freelist[slindex].pagenum;
+ block->link.next_offset = pool->freelist[slindex].offset;
+ pool->freelist[slindex].pagenum = pagenum;
+ pool->freelist[slindex].offset = offset;
+
+ if (block->link.next_pagenum) {
+ nextblock = get_ptr_atomic(block->link.next_pagenum,
+ block->link.next_offset, KM_USER1);
+ nextblock->link.prev_pagenum = pagenum;
+ nextblock->link.prev_offset = offset;
+ put_ptr_atomic(nextblock, KM_USER1);
+ }
+
+ __set_bit(slindex % BITS_PER_LONG, &pool->slbitmap[flindex]);
+ __set_bit(flindex, &pool->flbitmap);
+}
+
+/*
+ * Remove block from head of freelist. Index 'slindex' identifies the freelist.
+ */
+static void remove_block_head(struct xv_pool *pool,
+ struct block_header *block, u32 slindex)
+{
+ struct block_header *tmpblock;
+ u32 flindex = slindex / BITS_PER_LONG;
+
+ pool->freelist[slindex].pagenum = block->link.next_pagenum;
+ pool->freelist[slindex].offset = block->link.next_offset;
+ block->link.prev_pagenum = 0;
+ block->link.prev_offset = 0;
+
+ if (!pool->freelist[slindex].pagenum) {
+ __clear_bit(slindex % BITS_PER_LONG, &pool->slbitmap[flindex]);
+ if (!pool->slbitmap[flindex])
+ __clear_bit(flindex, &pool->flbitmap);
+ } else {
+ /*
+ * DEBUG ONLY: We need not reinitialize freelist head previous
+ * pointer to 0 - we never depend on its value. But just for
+ * sanity, lets do it.
+ */
+ tmpblock = get_ptr_atomic(pool->freelist[slindex].pagenum,
+ pool->freelist[slindex].offset, KM_USER1);
+ tmpblock->link.prev_pagenum = 0;
+ tmpblock->link.prev_offset = 0;
+ put_ptr_atomic(tmpblock, KM_USER1);
+ }
+}
+
+/*
+ * Remove block from freelist. Index 'slindex' identifies the freelist.
+ */
+static void remove_block(struct xv_pool *pool, u32 pagenum, u32 offset,
+ struct block_header *block, u32 slindex)
+{
+ u32 flindex;
+ struct block_header *tmpblock;
+
+ if (pool->freelist[slindex].pagenum == pagenum
+ && pool->freelist[slindex].offset == offset) {
+ remove_block_head(pool, block, slindex);
+ return;
+ }
+
+ flindex = slindex / BITS_PER_LONG;
+
+ if (block->link.prev_pagenum) {
+ tmpblock = get_ptr_atomic(block->link.prev_pagenum,
+ block->link.prev_offset, KM_USER1);
+ tmpblock->link.next_pagenum = block->link.next_pagenum;
+ tmpblock->link.next_offset = block->link.next_offset;
+ put_ptr_atomic(tmpblock, KM_USER1);
+ }
+
+ if (block->link.next_pagenum) {
+ tmpblock = get_ptr_atomic(block->link.next_pagenum,
+ block->link.next_offset, KM_USER1);
+ tmpblock->link.prev_pagenum = block->link.prev_pagenum;
+ tmpblock->link.prev_offset = block->link.prev_offset;
+ put_ptr_atomic(tmpblock, KM_USER1);
+ }
+
+ return;
+}
+
+/*
+ * Allocate a page and add it freelist of given pool.
+ */
+static int grow_pool(struct xv_pool *pool, gfp_t flags)
+{
+ u32 pagenum;
+ struct block_header *block;
+
+ pagenum = xv_alloc_page(flags);
+ if (unlikely(!pagenum))
+ return -ENOMEM;
+
+ stat_inc(&pool->total_pages);
+
+ spin_lock(&pool->lock);
+ block = get_ptr_atomic(pagenum, 0, KM_USER0);
+
+ block->size = PAGE_SIZE - XV_ALIGN;
+ set_flag(block, BLOCK_FREE);
+ clear_flag(block, PREV_FREE);
+ set_blockprev(block, 0);
+
+ insert_block(pool, pagenum, 0, block);
+
+ put_ptr_atomic(block, KM_USER0);
+ spin_unlock(&pool->lock);
+
+ return 0;
+}
+
+/*
+ * Create a memory pool. Allocates freelist, bitmaps and other
+ * per-pool metadata.
+ */
+struct xv_pool *xv_create_pool(void)
+{
+ u32 ovhd_size;
+ struct xv_pool *pool;
+
+ ovhd_size = roundup(sizeof(*pool), PAGE_SIZE);
+ pool = kzalloc(ovhd_size, GFP_KERNEL);
+ if (!pool)
+ return NULL;
+
+ spin_lock_init(&pool->lock);
+
+ return pool;
+}
+EXPORT_SYMBOL_GPL(xv_create_pool);
+
+void xv_destroy_pool(struct xv_pool *pool)
+{
+ kfree(pool);
+}
+EXPORT_SYMBOL_GPL(xv_destroy_pool);
+
+/**
+ * xv_malloc - Allocate block of given size from pool.
+ * @pool: pool to allocate from
+ * @size: size of block to allocate
+ * @pagenum: page no. that holds the object
+ * @offset: location of object within pagenum
+ *
+ * On success, <pagenum, offset> identifies block allocated
+ * and 0 is returned. On failure, <pagenum, offset> is set to
+ * 0 and -ENOMEM is returned.
+ *
+ * Allocation requests with size > XV_MAX_ALLOC_SIZE will fail.
+ */
+int xv_malloc(struct xv_pool *pool, u32 size, u32 *pagenum, u32 *offset,
+ gfp_t flags)
+{
+ int error;
+ u32 index, tmpsize, origsize, tmpoffset;
+ struct block_header *block, *tmpblock;
+
+ *pagenum = 0;
+ *offset = 0;
+ origsize = size;
+
+ if (unlikely(!size || size > XV_MAX_ALLOC_SIZE))
+ return -ENOMEM;
+
+ size = ALIGN(size, XV_ALIGN);
+
+ spin_lock(&pool->lock);
+
+ index = find_block(pool, size, pagenum, offset);
+
+ if (!*pagenum) {
+ spin_unlock(&pool->lock);
+ if (flags & GFP_NOWAIT)
+ return -ENOMEM;
+ error = grow_pool(pool, flags);
+ if (unlikely(error))
+ return -ENOMEM;
+
+ spin_lock(&pool->lock);
+ index = find_block(pool, size, pagenum, offset);
+ }
+
+ if (!*pagenum) {
+ spin_unlock(&pool->lock);
+ return -ENOMEM;
+ }
+
+ block = get_ptr_atomic(*pagenum, *offset, KM_USER0);
+
+ remove_block_head(pool, block, index);
+
+ /* Split the block if required */
+ tmpoffset = *offset + size + XV_ALIGN;
+ tmpsize = block->size - size;
+ tmpblock = (struct block_header *)((char *)block + size + XV_ALIGN);
+ if (tmpsize) {
+ tmpblock->size = tmpsize - XV_ALIGN;
+ set_flag(tmpblock, BLOCK_FREE);
+ clear_flag(tmpblock, PREV_FREE);
+
+ set_blockprev(tmpblock, *offset);
+ if (tmpblock->size >= XV_MIN_ALLOC_SIZE)
+ insert_block(pool, *pagenum, tmpoffset, tmpblock);
+
+ if (tmpoffset + XV_ALIGN + tmpblock->size != PAGE_SIZE) {
+ tmpblock = BLOCK_NEXT(tmpblock);
+ set_blockprev(tmpblock, tmpoffset);
+ }
+ } else {
+ /* This block is exact fit */
+ if (tmpoffset != PAGE_SIZE)
+ clear_flag(tmpblock, PREV_FREE);
+ }
+
+ block->size = origsize;
+ clear_flag(block, BLOCK_FREE);
+
+ put_ptr_atomic(block, KM_USER0);
+ spin_unlock(&pool->lock);
+
+ *offset += XV_ALIGN;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(xv_malloc);
+
+/*
+ * Free block identified with <pagenum, offset>
+ */
+void xv_free(struct xv_pool *pool, u32 pagenum, u32 offset)
+{
+ void *page;
+ struct block_header *block, *tmpblock;
+
+ offset -= XV_ALIGN;
+
+ spin_lock(&pool->lock);
+
+ page = get_ptr_atomic(pagenum, 0, KM_USER0);
+ block = (struct block_header *)((char *)page + offset);
+
+ /* Catch double free bugs */
+ BUG_ON(test_flag(block, BLOCK_FREE));
+
+ block->size = ALIGN(block->size, XV_ALIGN);
+
+ tmpblock = BLOCK_NEXT(block);
+ if (offset + block->size + XV_ALIGN == PAGE_SIZE)
+ tmpblock = NULL;
+
+ /* Merge next block if its free */
+ if (tmpblock && test_flag(tmpblock, BLOCK_FREE)) {
+ /*
+ * Blocks smaller than XV_MIN_ALLOC_SIZE
+ * are not inserted in any free list.
+ */
+ if (tmpblock->size >= XV_MIN_ALLOC_SIZE) {
+ remove_block(pool, pagenum,
+ offset + block->size + XV_ALIGN, tmpblock,
+ get_index_for_insert(tmpblock->size));
+ }
+ block->size += tmpblock->size + XV_ALIGN;
+ }
+
+ /* Merge previous block if its free */
+ if (test_flag(block, PREV_FREE)) {
+ tmpblock = (struct block_header *)((char *)(page) +
+ get_blockprev(block));
+ offset = offset - tmpblock->size - XV_ALIGN;
+
+ if (tmpblock->size >= XV_MIN_ALLOC_SIZE)
+ remove_block(pool, pagenum, offset, tmpblock,
+ get_index_for_insert(tmpblock->size));
+
+ tmpblock->size += block->size + XV_ALIGN;
+ block = tmpblock;
+ }
+
+ /* No used objects in this page. Free it. */
+ if (block->size == PAGE_SIZE - XV_ALIGN) {
+ put_ptr_atomic(page, KM_USER0);
+ spin_unlock(&pool->lock);
+
+ xv_free_page(pagenum);
+ stat_dec(&pool->total_pages);
+ return;
+ }
+
+ set_flag(block, BLOCK_FREE);
+ if (block->size >= XV_MIN_ALLOC_SIZE)
+ insert_block(pool, pagenum, offset, block);
+
+ if (offset + block->size + XV_ALIGN != PAGE_SIZE) {
+ tmpblock = BLOCK_NEXT(block);
+ set_flag(tmpblock, PREV_FREE);
+ set_blockprev(tmpblock, offset);
+ }
+
+ put_ptr_atomic(page, KM_USER0);
+ spin_unlock(&pool->lock);
+
+ return;
+}
+EXPORT_SYMBOL_GPL(xv_free);
+
+u32 xv_get_object_size(void *obj)
+{
+ struct block_header *blk;
+
+ blk = (struct block_header *)((char *)(obj) - XV_ALIGN);
+ return blk->size;
+}
+EXPORT_SYMBOL_GPL(xv_get_object_size);
+
+/*
+ * Returns total memory used by allocator (userdata + metadata)
+ */
+u64 xv_get_total_size_bytes(struct xv_pool *pool)
+{
+ return pool->total_pages << PAGE_SHIFT;
+}
+EXPORT_SYMBOL_GPL(xv_get_total_size_bytes);
+
+static int __init xv_malloc_init(void)
+{
+ return 0;
+}
+
+static void __exit xv_malloc_exit(void)
+{
+ return;
+}
+
+module_init(xv_malloc_init);
+module_exit(xv_malloc_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
+MODULE_DESCRIPTION("xvmalloc memory allocator");
--- /dev/null
+/*
+ * xvmalloc.h
+ *
+ * Copyright (C) 2008, 2009 Nitin Gupta
+ *
+ * This code is released using a dual license strategy: GPL/LGPL
+ * You can choose the licence that better fits your requirements.
+ *
+ * Released under the terms of GNU General Public License Version 2.0
+ * Released under the terms of GNU Lesser General Public License Version 2.1
+ */
+
+#ifndef _XVMALLOC_H_
+#define _XVMALLOC_H_
+
+#include <linux/types.h>
+
+struct xv_pool;
+
+struct xv_pool *xv_create_pool(void);
+void xv_destroy_pool(struct xv_pool *pool);
+
+int xv_malloc(struct xv_pool *pool, u32 size, u32 *pagenum, u32 *offset,
+ gfp_t flags);
+void xv_free(struct xv_pool *pool, u32 pagenum, u32 offset);
+
+u32 xv_get_object_size(void *obj);
+u64 xv_get_total_size_bytes(struct xv_pool *pool);
+
+#endif
--- /dev/null
+/*
+ * xvmalloc_int.c
+ *
+ * Copyright (C) 2008, 2009 Nitin Gupta
+ *
+ * This code is released using a dual license strategy: GPL/LGPL
+ * You can choose the licence that better fits your requirements.
+ *
+ * Released under the terms of GNU General Public License Version 2.0
+ * Released under the terms of GNU Lesser General Public License Version 2.1
+ */
+
+#ifndef _XVMALLOC_INT_H_
+#define _XVMALLOC_INT_H_
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+
+/* User configurable params */
+
+/* This must be greater than sizeof(LinkFree) */
+#define XV_MIN_ALLOC_SIZE 32
+#define XV_MAX_ALLOC_SIZE (PAGE_SIZE - XV_ALIGN)
+
+/* Must be power of two */
+#define XV_ALIGN_SHIFT 2
+#define XV_ALIGN (1 << XV_ALIGN_SHIFT)
+#define XV_ALIGN_MASK (XV_ALIGN - 1)
+
+/* Free lists are separated by FL_DELTA bytes */
+#define FL_DELTA_SHIFT 3
+#define FL_DELTA (1 << FL_DELTA_SHIFT)
+#define FL_DELTA_MASK (FL_DELTA - 1)
+#define NUM_FREE_LISTS ((XV_MAX_ALLOC_SIZE - XV_MIN_ALLOC_SIZE) \
+ / FL_DELTA + 1)
+
+#define MAX_FLI DIV_ROUND_UP(NUM_FREE_LISTS, BITS_PER_LONG)
+
+/* End of user params */
+
+enum blockflags {
+ BLOCK_FREE,
+ PREV_FREE,
+ __NR_BLOCKFLAGS,
+};
+
+#define FLAGS_MASK XV_ALIGN_MASK
+#define PREV_MASK (~FLAGS_MASK)
+
+struct freelist_entry {
+ u32 pagenum;
+ u16 offset;
+ u16 pad;
+};
+
+struct link_free {
+ u32 prev_pagenum;
+ u32 next_pagenum;
+ u16 prev_offset;
+ u16 next_offset;
+};
+
+struct block_header {
+ union {
+ /* This common header must be ALIGN bytes */
+ u8 common[XV_ALIGN];
+ struct {
+ u16 size;
+ u16 prev;
+ };
+ };
+ struct link_free link;
+};
+
+struct xv_pool {
+ ulong flbitmap;
+ ulong slbitmap[MAX_FLI];
+ spinlock_t lock;
+
+ struct freelist_entry freelist[NUM_FREE_LISTS];
+
+ /* stats */
+ u64 total_pages;
+};
+
+#endif
projects / linux-flexiantxendom0-natty.git / commitdiff