Re: [BK] ReiserFS changesets for 2.4 (performs writes more than 4k at a time)

Hans Reiser
2002-09-11T17:34:45Z

Thanks for benchmarks. It suggests that the new code doesn't scale to
lots of threads as well as the old, but performs much better for single
threads. Maybe Oleg can comment on why that might be --- I have no idea.

On the whole it looks like a win, but why more threads perform worse in
some cases probably is worth trying to understand. Maybe we should have
a seminar on exactly what tiobench is doing and how it interacts with
this code.

Hans

Arador wrote:

>On Tue, 10 Sep 2002 15:16:51 -0300 (BRT)
>Marcelo Tosatti <marcelo@conectiva.com.br> escribió:
>
>
>
>>Huh, now that I released -pre6 _with_ this stuff by accident its too late.
>>Silly me.
>>
>>Can you make me a tree which backouts the big write code please?
>>
>>Will be releasing a -pre7 shortly due to that.
>>
>>
>
>Although some changes are going to be removed in -pre7, i've run tiobench to test the changes.
>Kernel versions are plain -pre4 and -pre6
>
>Unit information
>================
>File size = megabytes
>Blk Size = bytes
>Rate = megabytes per second
>CPU% = percentage of CPU used during the test
>Latency = milliseconds
>Lat% = percent of requests that took longer than X seconds
>CPU Eff = Rate divided by CPU% - throughput per cpu load
>
>Sequential Reads
> File Blk Num Avg Maximum Lat% Lat% CPU
>Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff
>---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- -----
>2.4.20-pre4 200 4096 1 11.78 28.50% 0.328 146.54 0.00000 0.00000 41
>2.4.20-pre4 200 4096 2 10.30 23.02% 0.709 1349.77 0.00000 0.00000 45
>2.4.20-pre4 200 4096 4 9.14 22.06% 1.585 1309.01 0.00000 0.00000 41
>2.4.20-pre4 200 4096 8 8.92 21.84% 2.751 1472.06 0.00000 0.00000 41
>
>Random Reads
> File Blk Num Avg Maximum Lat% Lat% CPU
>Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff
>---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- -----
>2.4.20-pre4 200 4096 1 0.53 2.389% 7.307 20.08 0.00000 0.00000 22
>2.4.20-pre4 200 4096 2 0.55 2.201% 14.157 39.98 0.00000 0.00000 25
>2.4.20-pre4 200 4096 4 0.55 2.766% 27.646 80.48 0.00000 0.00000 20
>2.4.20-pre4 200 4096 8 0.60 2.527% 49.805 159.53 0.00000 0.00000 24
>
>Sequential Writes
> File Blk Num Avg Maximum Lat% Lat% CPU
>Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff
>---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- -----
>2.4.20-pre4 200 4096 1 10.76 80.14% 0.348 1100.04 0.00000 0.00000 13
>2.4.20-pre4 200 4096 2 11.63 87.26% 0.637 294.75 0.00000 0.00000 13
>2.4.20-pre4 200 4096 4 11.42 85.24% 1.258 424.02 0.00000 0.00000 13
>2.4.20-pre4 200 4096 8 11.49 84.29% 2.514 745.41 0.00000 0.00000 14
>
>Random Writes
> File Blk Num Avg Maximum Lat% Lat% CPU
>Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff
>---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- -----
>2.4.20-pre4 200 4096 1 1.13 3.620% 0.131 1.94 0.00000 0.00000 31
>2.4.20-pre4 200 4096 2 1.18 3.770% 0.254 22.61 0.00000 0.00000 31
>2.4.20-pre4 200 4096 4 1.14 4.002% 0.483 42.89 0.00000 0.00000 28
>2.4.20-pre4 200 4096 8 1.19 4.048% 0.930 83.60 0.00000 0.00000 29
>root@diego:/home/diego/kernel/tiobench/tiobench-0.3.3#
>
>Unit information
>================
>File size = megabytes
>Blk Size = bytes
>Rate = megabytes per second
>CPU% = percentage of CPU used during the test
>Latency = milliseconds
>Lat% = percent of requests that took longer than X seconds
>CPU Eff = Rate divided by CPU% - throughput per cpu load
>
>Sequential Reads
> File Blk Num Avg Maximum Lat% Lat% CPU
>Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff
>---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- -----
>2.4.20-pre6 200 4096 1 12.16 29.78% 0.317 135.42 0.00000 0.00000 41
>2.4.20-pre6 200 4096 2 10.20 23.96% 0.697 1226.99 0.00000 0.00000 43
>2.4.20-pre6 200 4096 4 9.49 23.14% 1.409 1197.27 0.00000 0.00000 41
>2.4.20-pre6 200 4096 8 8.36 21.69% 2.970 5532.30 0.00391 0.00000 39
>
>Random Reads
> File Blk Num Avg Maximum Lat% Lat% CPU
>Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff
>---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- -----
>2.4.20-pre6 200 4096 1 0.55 2.037% 7.106 30.01 0.00000 0.00000 27
>2.4.20-pre6 200 4096 2 0.54 2.118% 14.170 40.09 0.00000 0.00000 26
>2.4.20-pre6 200 4096 4 0.56 2.308% 27.007 79.38 0.00000 0.00000 24
>2.4.20-pre6 200 4096 8 0.58 2.593% 51.235 321.18 0.00000 0.00000 22
>
>Sequential Writes
> File Blk Num Avg Maximum Lat% Lat% CPU
>Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff
>---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- -----
>2.4.20-pre6 200 4096 1 12.01 87.73% 0.311 280.04 0.00000 0.00000 14
>2.4.20-pre6 200 4096 2 11.36 83.79% 0.645 509.40 0.00000 0.00000 14
>2.4.20-pre6 200 4096 4 11.58 85.63% 1.261 528.34 0.00000 0.00000 14
>2.4.20-pre6 200 4096 8 9.67 69.58% 2.986 2158.01 0.00195 0.00000 14
>
>Random Writes
> File Blk Num Avg Maximum Lat% Lat% CPU
>Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff
>---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- -----
>2.4.20-pre6 200 4096 1 1.19 4.191% 0.130 0.76 0.00000 0.00000 28
>2.4.20-pre6 200 4096 2 1.16 4.067% 0.255 23.82 0.00000 0.00000 28
>2.4.20-pre6 200 4096 4 1.23 4.159% 0.495 42.33 0.00000 0.00000 29
>2.4.20-pre6 200 4096 8 1.21 4.432% 1.270 228.09 0.00000 0.00000 27
>root@diego:/home/diego/kernel/tiobench/tiobench-0.3.3#
>
>
>
>Diego Calleja
>
>
>
>
>