pfn_to_page and page_to_pfn operations. This is the most
efficient option when sufficient kernel resources are available.
+config HAVE_MEMBLOCK
+ boolean
+
+config HAVE_MEMBLOCK_NODE_MAP
+ boolean
+
+config ARCH_DISCARD_MEMBLOCK
+ boolean
+
+config NO_BOOTMEM
+ boolean
+
# eventually, we can have this option just 'select SPARSEMEM'
config MEMORY_HOTPLUG
bool "Allow for memory hot-add"
config COMPACTION
bool "Allow for memory compaction"
select MIGRATION
- depends on EXPERIMENTAL && HUGETLB_PAGE && MMU
+ depends on MMU
help
Allows the compaction of memory for the allocation of huge pages.
config MIGRATION
bool "Page migration"
def_bool y
- depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE
+ depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION
help
Allows the migration of the physical location of pages of processes
while the virtual addresses are not changed. This is useful in
See Documentation/nommu-mmap.txt for more information.
+config TRANSPARENT_HUGEPAGE
+ bool "Transparent Hugepage Support"
+ depends on X86 && !XEN && MMU
+ select COMPACTION
+ help
+ Transparent Hugepages allows the kernel to use huge pages and
+ huge tlb transparently to the applications whenever possible.
+ This feature can improve computing performance to certain
+ applications by speeding up page faults during memory
+ allocation, by reducing the number of tlb misses and by speeding
+ up the pagetable walking.
+
+ If memory constrained on embedded, you may want to say N.
+
+choice
+ prompt "Transparent Hugepage Support sysfs defaults"
+ depends on TRANSPARENT_HUGEPAGE
+ default TRANSPARENT_HUGEPAGE_ALWAYS
+ help
+ Selects the sysfs defaults for Transparent Hugepage Support.
+
+ config TRANSPARENT_HUGEPAGE_ALWAYS
+ bool "always"
+ help
+ Enabling Transparent Hugepage always, can increase the
+ memory footprint of applications without a guaranteed
+ benefit but it will work automatically for all applications.
+
+ config TRANSPARENT_HUGEPAGE_MADVISE
+ bool "madvise"
+ help
+ Enabling Transparent Hugepage madvise, will only provide a
+ performance improvement benefit to the applications using
+ madvise(MADV_HUGEPAGE) but it won't risk to increase the
+ memory footprint of applications without a guaranteed
+ benefit.
+endchoice
+
#
-# support for transcendent memory
+# UP and nommu archs use km based percpu allocator
#
-config TMEM
+config NEED_PER_CPU_KM
+ depends on !SMP
bool
+ default y
+
+config CLEANCACHE
+ bool "Enable cleancache driver to cache clean pages if tmem is present"
+ default n
help
- In a virtualized environment, allows unused and underutilized
- system physical memory to be made accessible through a narrow
- well-defined page-copy-based API. If unsure, say Y.
-
-config PRECACHE
- bool "Cache clean pages in transcendent memory"
- depends on XEN
- select TMEM
- help
- Allows the transcendent memory pool to be used to store clean
- page-cache pages which, under some circumstances, will greatly
- reduce paging and thus improve performance. If unsure, say Y.
-
-config PRESWAP
- bool "Swap pages to transcendent memory"
- depends on XEN
- select TMEM
+ Cleancache can be thought of as a page-granularity victim cache
+ for clean pages that the kernel's pageframe replacement algorithm
+ (PFRA) would like to keep around, but can't since there isn't enough
+ memory. So when the PFRA "evicts" a page, it first attempts to use
+ cleancache code to put the data contained in that page into
+ "transcendent memory", memory that is not directly accessible or
+ addressable by the kernel and is of unknown and possibly
+ time-varying size. And when a cleancache-enabled
+ filesystem wishes to access a page in a file on disk, it first
+ checks cleancache to see if it already contains it; if it does,
+ the page is copied into the kernel and a disk access is avoided.
+ When a transcendent memory driver is available (such as zcache or
+ Xen transcendent memory), a significant I/O reduction
+ may be achieved. When none is available, all cleancache calls
+ are reduced to a single pointer-compare-against-NULL resulting
+ in a negligible performance hit.
+
+ If unsure, say Y to enable cleancache
+
+config FRONTSWAP
+ bool "Enable frontswap to cache swap pages if tmem is present"
+ depends on SWAP
+ default n
help
- Allows the transcendent memory pool to be used as a pseudo-swap
- device which, under some circumstances, will greatly reduce
- swapping and thus improve performance. If unsure, say Y.
+ Frontswap is so named because it can be thought of as the opposite
+ of a "backing" store for a swap device. The data is stored into
+ "transcendent memory", memory that is not directly accessible or
+ addressable by the kernel and is of unknown and possibly
+ time-varying size. When space in transcendent memory is available,
+ a significant swap I/O reduction may be achieved. When none is
+ available, all frontswap calls are reduced to a single pointer-
+ compare-against-NULL resulting in a negligible performance hit
+ and swap data is stored as normal on the matching swap device.
+
+ If unsure, say Y to enable frontswap.
projects / linux-flexiantxendom0-3.2.10.git / blobdiff