From: Ojaswin Mujoo ojaswin@linux.ibm.com
commit 077d0c2c78df6f7260cdd015a991327efa44d8ad upstream.
Currently mb_optimize_scan scan feature which improves filesystem performance heavily (when FS is fragmented), seems to be not working with files with extents (ext4 by default has files with extents).
This patch fixes that and makes mb_optimize_scan feature work for files with extents.
Below are some performance numbers obtained when allocating a 10M and 100M file with and w/o this patch on a filesytem with no 1M contiguous block.
<perf numbers> =============== Workload: dd if=/dev/urandom of=test conv=fsync bs=1M count=10/100
Time taken ===================================================== no. Size without-patch with-patch Diff(%) 1 10M 0m8.401s 0m5.623s 33.06% 2 100M 1m40.465s 1m14.737s 25.6%
<debug stats> ============= w/o patch: mballoc: reqs: 17056 success: 11407 groups_scanned: 13643 cr0_stats: hits: 37 groups_considered: 9472 useless_loops: 36 bad_suggestions: 0 cr1_stats: hits: 11418 groups_considered: 908560 useless_loops: 1894 bad_suggestions: 0 cr2_stats: hits: 1873 groups_considered: 6913 useless_loops: 21 cr3_stats: hits: 21 groups_considered: 5040 useless_loops: 21 extents_scanned: 417364 goal_hits: 3707 2^n_hits: 37 breaks: 1873 lost: 0 buddies_generated: 239/240 buddies_time_used: 651080 preallocated: 705 discarded: 478
with patch: mballoc: reqs: 12768 success: 11305 groups_scanned: 12768 cr0_stats: hits: 1 groups_considered: 18 useless_loops: 0 bad_suggestions: 0 cr1_stats: hits: 5829 groups_considered: 50626 useless_loops: 0 bad_suggestions: 0 cr2_stats: hits: 6938 groups_considered: 580363 useless_loops: 0 cr3_stats: hits: 0 groups_considered: 0 useless_loops: 0 extents_scanned: 309059 goal_hits: 0 2^n_hits: 1 breaks: 1463 lost: 0 buddies_generated: 239/240 buddies_time_used: 791392 preallocated: 673 discarded: 446
Fixes: 196e402 (ext4: improve cr 0 / cr 1 group scanning) Cc: stable@kernel.org Reported-by: Geetika Moolchandani Geetika.Moolchandani1@ibm.com Reported-by: Nageswara R Sastry rnsastry@linux.ibm.com Suggested-by: Ritesh Harjani riteshh@linux.ibm.com Signed-off-by: Ojaswin Mujoo ojaswin@linux.ibm.com Link: https://lore.kernel.org/r/fc9a48f7f8dcfc83891a8b21f6dd8cdf056ed810.164673269... Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ext4/mballoc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -1000,7 +1000,7 @@ static inline int should_optimize_scan(s return 0; if (ac->ac_criteria >= 2) return 0; - if (ext4_test_inode_flag(ac->ac_inode, EXT4_INODE_EXTENTS)) + if (!ext4_test_inode_flag(ac->ac_inode, EXT4_INODE_EXTENTS)) return 0; return 1; }