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Subjectbig ext3 sequential write improvement in 2.5.51-mm1 gone in 2.5.53-mm1?
From
On a quad xeon running tiobench...
The throughput and max latency for ext3 sequential writes
looks very good when threads >= 2 on 2.5.51-mm1.

Did 2.5.51-mm1 mount ext3 as ext2? I have ext2 logs for
2.5.51-mm1 and they look similar to the ext3 results.
The other 2.5 kernels from around that time look more
like 2.5.53-mm1.

file size = 8192 megs
block size = 4096 bytes
rate in megabytes/second
latency in milliseconds

Sequential Writes
Num Avg Maximum Lat% Lat% CPU
Identifier Thr Rate (CPU%) Latency Latency >2s >10s Eff
------------ --- ------ ------ --------- ----------- -------- -------- -----
2.5.51-mm1 1 55.58 46.70% 0.234 18461.07 0.00834 0.00000 119
2.5.51-mm1 2 38.00 31.54% 0.563 18460.95 0.00896 0.00000 120
2.5.51-mm1 4 35.28 32.69% 1.041 84910.77 0.01306 0.00057 108
2.5.51-mm1 8 34.86 32.97% 2.090 113261.88 0.02433 0.00387 106
2.5.51-mm1 16 34.79 32.80% 3.786 216278.13 0.02923 0.01054 106
2.5.51-mm1 32 33.25 32.31% 7.083 331456.04 0.03152 0.01411 103
2.5.51-mm1 64 31.77 32.14% 14.020 604095.22 0.03772 0.02094 99
2.5.51-mm1 128 30.59 31.60% 25.436 653761.04 0.04019 0.02298 97
2.5.51-mm1 256 32.45 34.83% 47.633 598925.79 0.06914 0.04615 93

Sequential Writes
Num Avg Maximum Lat% Lat% CPU
Identifier Thr Rate (CPU%) Latency Latency >2s >10s Eff
------------ --- ------ ------ --------- ----------- -------- -------- -----
2.5.53-mm1 1 52.74 68.60% 0.604 19544.48 0.01731 0.00000 77
2.5.53-mm1 2 2.70 4.951% 7.589 54571.99 0.12716 0.00739 55
2.5.53-mm1 4 2.78 34.78% 13.966 467805.71 0.16842 0.03018 8
2.5.53-mm1 8 2.93 59.73% 26.819 1008655.17 0.19922 0.04420 5
2.5.53-mm1 16 3.14 26.13% 45.610 1939797.82 0.14705 0.05607 12
2.5.53-mm1 32 3.35 19.17% 80.421 3055837.66 0.12188 0.04888 17
2.5.53-mm1 64 3.43 15.13% 163.323 4284106.34 0.11868 0.05264 23
2.5.53-mm1 128 3.66 20.04% 260.372 5148947.62 0.12889 0.04530 18
2.5.53-mm1 256 4.26 20.30% 382.981 3094442.29 0.20232 0.06323 21

There is another odd thing in some of the 2.5 ext3 results. Several of the
kernels show a jump in throughput at 256 threads.

Sequential Writes
Num Avg Maximum Lat% Lat% CPU
Identifier Thr Rate (CPU%) Latency Latency >2s >10s Eff
------------ --- ------ ------ --------- ----------- -------- -------- -----
2.5.56 1 53.17 69.99% 0.194 36612.36 0.00029 0.00005 76
2.5.56 2 2.53 4.728% 7.549 1219600.59 0.05112 0.00205 53
2.5.56 4 2.58 73.97% 15.141 823168.02 0.05078 0.01531 3
2.5.56 8 2.67 179.9% 29.981 641722.67 0.07091 0.04382 1
2.5.56 16 3.34 136.6% 47.075 1416051.92 0.11807 0.09304 2
2.5.56 32 2.93 124.8% 100.112 1842078.09 0.18826 0.14262 2
2.5.56 64 3.66 37.46% 147.693 4216304.67 0.12394 0.06661 10
2.5.56 128 4.01 17.11% 237.592 4194864.65 0.10777 0.05642 23
2.5.56 256 12.64 48.78% 353.895 3741404.43 0.10434 0.05335 26

2.4 has a more gentle degradation in throughput and max latency for seq writes
on ext3:

Sequential Writes
Num Avg Maximum Lat% Lat% CPU
Identifier Thr Rate (CPU%) Latency Latency >2s >10s Eff
------------- --- ------ ------ --------- ----------- -------- -------- -----
2.4.20-pre10 1 37.71 56.08% 0.288 4315.58 0.00000 0.00000 67
2.4.20-pre10 2 33.01 98.65% 0.592 5517.10 0.00010 0.00000 33
2.4.20-pre10 4 30.83 153.3% 1.162 3684.74 0.00000 0.00000 20
2.4.20-pre10 8 24.86 126.9% 2.523 7436.22 0.00058 0.00000 20
2.4.20-pre10 16 21.21 104.0% 4.893 9132.94 0.00992 0.00000 20
2.4.20-pre10 32 18.14 97.27% 10.394 13451.42 0.09843 0.00000 19
2.4.20-pre10 64 15.63 90.39% 22.679 18888.44 0.39897 0.00000 17
2.4.20-pre10 128 12.03 78.06% 54.387 31156.69 1.12638 0.00038 15
2.4.20-pre10 256 9.94 71.13% 134.323 61604.97 2.87437 0.03022 14

--
Randy Hron
http://home.earthlink.net/~rwhron/kernel/bigbox.html

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