From 81ee68a0ce45214c71314c4191c7606ca2844d93 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Mon, 16 Apr 2012 12:16:20 -0400 Subject: [PATCH] ext4: address scalability issue by removing extent cache statistics BugLink: http://bugs.launchpad.net/bugs/987337 commit 9cd70b347e9761ea2d2ac3d758c529a48a8193e6 upstream. Andi Kleen and Tim Chen have reported that under certain circumstances the extent cache statistics are causing scalability problems due to cache line bounces. Signed-off-by: "Theodore Ts'o" Signed-off-by: Greg Kroah-Hartman Signed-off-by: Tim Gardner --- fs/ext4/ext4.h | 3 --- fs/ext4/extents.c | 4 ---- fs/ext4/super.c | 16 ---------------- 3 files changed, 23 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index dbae4d9..7b1cd5c 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1185,9 +1185,6 @@ struct ext4_sb_info { unsigned long s_ext_blocks; unsigned long s_ext_extents; #endif - /* ext4 extent cache stats */ - unsigned long extent_cache_hits; - unsigned long extent_cache_misses; /* for buddy allocator */ struct ext4_group_info ***s_group_info; diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 7507036..c2a2012 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -2052,10 +2052,6 @@ static int ext4_ext_check_cache(struct inode *inode, ext4_lblk_t block, ret = 1; } errout: - if (!ret) - sbi->extent_cache_misses++; - else - sbi->extent_cache_hits++; trace_ext4_ext_in_cache(inode, block, ret); spin_unlock(&EXT4_I(inode)->i_block_reservation_lock); return ret; diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 9281dbe..961059b 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2504,18 +2504,6 @@ static ssize_t lifetime_write_kbytes_show(struct ext4_attr *a, EXT4_SB(sb)->s_sectors_written_start) >> 1))); } -static ssize_t extent_cache_hits_show(struct ext4_attr *a, - struct ext4_sb_info *sbi, char *buf) -{ - return snprintf(buf, PAGE_SIZE, "%lu\n", sbi->extent_cache_hits); -} - -static ssize_t extent_cache_misses_show(struct ext4_attr *a, - struct ext4_sb_info *sbi, char *buf) -{ - return snprintf(buf, PAGE_SIZE, "%lu\n", sbi->extent_cache_misses); -} - static ssize_t inode_readahead_blks_store(struct ext4_attr *a, struct ext4_sb_info *sbi, const char *buf, size_t count) @@ -2573,8 +2561,6 @@ static struct ext4_attr ext4_attr_##name = __ATTR(name, mode, show, store) EXT4_RO_ATTR(delayed_allocation_blocks); EXT4_RO_ATTR(session_write_kbytes); EXT4_RO_ATTR(lifetime_write_kbytes); -EXT4_RO_ATTR(extent_cache_hits); -EXT4_RO_ATTR(extent_cache_misses); EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, sbi_ui_show, inode_readahead_blks_store, s_inode_readahead_blks); EXT4_RW_ATTR_SBI_UI(inode_goal, s_inode_goal); @@ -2590,8 +2576,6 @@ static struct attribute *ext4_attrs[] = { ATTR_LIST(delayed_allocation_blocks), ATTR_LIST(session_write_kbytes), ATTR_LIST(lifetime_write_kbytes), - ATTR_LIST(extent_cache_hits), - ATTR_LIST(extent_cache_misses), ATTR_LIST(inode_readahead_blks), ATTR_LIST(inode_goal), ATTR_LIST(mb_stats), -- 1.7.10.4