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)
Reported-by: Geetika Moolchandani <Geetika.Moolchandani1@xxxxxxx>
Reported-by: Nageswara R Sastry <rnsastry@xxxxxxxxxxxxx>
Suggested-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>
Signed-off-by: Ojaswin Mujoo <ojaswin@xxxxxxxxxxxxx>
---
fs/ext4/mballoc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 67ac95c4cd9b..f9be6ab482a5 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -1000,7 +1000,7 @@ static inline int should_optimize_scan(struct ext4_allocation_context *ac)
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;
}
--
2.27.0
