https://bugzilla.kernel.org/show_bug.cgi?id=43013
--- Comment #7 from ITec <itec@xxxxxxxxxxxxxxxxxxx> 2012-03-30 15:34:38 ---
(Second attempt to post this:)
Yes, I know, that there are many things that could affect the test.
And I am not speaking about loss of "some" performance. I am speaking about
loss of 98% performance.
But what could cause this?
And why does it happen only on 3.2+?
About fragmentation:
# xfs_fsr -v /dev/sda3
/ start inode=0
ino=20294080
ino=20294080 already fully defragmented.
# df -m /tmp
Filesystem 1M-blocks Used Available Use% Mounted on
/dev/sda3 15248 2549 12700 17% /
# dd if=/dev/zero of=/tmp/zero1.tmp bs=1024 count=9000000
9000000+0 records in
9000000+0 records out
9216000000 bytes (9,2 GB) copied, 396,978 s, 23,2 MB/s
The first 8GB go with 100MB/s the rest with 1.9MB/s.
# xfs_bmap /tmp/zero1.tmp
/tmp/zero1.tmp:
0: [0..4194303]: 26708152..30902455
1: [4194304..8388607]: 11237112..15431415
2: [8388608..12076735]: 4123968..7812095
3: [12076736..15671151]: 19841872..23436287
4: [15671152..16201615]: 18355464..18885927
5: [16201616..16547543]: 30902456..31248383
6: [16547544..16797911]: 3523816..3774183
7: [16797912..16816479]: 3783176..3801743
8: [16816480..16835343]: 3804000..3822863
9: [16835344..16950519]: 15431416..15546591
10: [16950520..16950551]: 15546600..15546631
11: [16950552..17065255]: 10757704..10872407
12: [17065256..17065295]: 10873000..10873039
13: [17065296..17083887]: 10739112..10757703
14: [17083888..17102567]: 10720432..10739111
15: [17102568..17219047]: 10603952..10720431
16: [17219048..17219079]: 10603920..10603951
17: [17219080..17241775]: 10581224..10603919
18: [17241776..17262391]: 10560608..10581223
19: [17262392..17283671]: 10539328..10560607
20: [17283672..17302879]: 10018552..10037759
21: [17302880..17302887]: 10037976..10037983
22: [17302888..17323039]: 9998400..10018551
23: [17323040..17342535]: 9966824..9986319
24: [17342536..17573871]: 18960144..19191479
25: [17573872..17655255]: 19264640..19346023
26: [17655256..17688759]: 18919824..18953327
27: [17688760..17706695]: 18901888..18919823
28: [17706696..17725951]: 19191480..19210735
29: [17725952..17745271]: 18142008..18161327
30: [17745272..17764551]: 18122728..18142007
31: [17764552..17783799]: 18103480..18122727
32: [17783800..17861359]: 15546632..15624191
33: [17861360..17899223]: 25742880..25780743
34: [17899224..17969279]: 26181368..26251423
35: [17969280..17999999]: 26399192..26429911
# df -m /tmp
Filesystem 1M-blocks Used Available Use% Mounted on
/dev/sda3 15248 11338 3911 75% /
# rm /tmp/zero1.tmp
dd if=/dev/zero of=/tmp/zero1.tmp bs=1024 count=1000000; dd if=/dev/zero
of=/tmp/zero2.tmp bs=1024 count=8000000; echo syncing; time sync
1000000+0 records in
1000000+0 records out
1024000000 bytes (1,0 GB) copied, 7,62766 s, 134 MB/s
8000000+0 records in
8000000+0 records out
8192000000 bytes (8,2 GB) copied, 77,9598 s, 105 MB/s
syncing
real 0m2.602s
user 0m0.000s
sys 0m0.000s
# xfs_bmap /tmp/zero*
/tmp/zero1.tmp:
0: [0..1048575]: 26708152..27756727
1: [1048576..1999999]: 4123968..5075391
/tmp/zero2.tmp:
0: [0..2097151]: 27756728..29853879
1: [2097152..4194303]: 5172544..7269695
2: [4194304..8388607]: 11237112..15431415
3: [8388608..11983023]: 19841872..23436287
4: [11983024..13377527]: 29853880..31248383
5: [13377528..13919927]: 7269696..7812095
6: [13919928..14450391]: 18355464..18885927
7: [14450392..14790055]: 10532744..10872407
8: [14790056..15050135]: 18960144..19220223
9: [15050136..15308935]: 3523816..3782615
10: [15308936..15501711]: 15431416..15624191
11: [15501712..15598863]: 5075392..5172543
12: [15598864..15680247]: 19264640..19346023
13: [15680248..15750303]: 26181368..26251423
14: [15750304..15819727]: 26399192..26468615
15: [15819728..15888935]: 25742880..25812087
16: [15888936..15955831]: 18886432..18953327
17: [15955832..15999999]: 18117160..18161327
So, creating one file with 9GB takes about 400s, but one file with 1GB and
another file with 8GB takes about 90s together.
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