Messages in this thread | ![/](/images/icornerl.gif) | | From | Jeff Moyer <> | Subject | Re: [PATCH] cfq-iosched: reduce write depth only if sync was delayed | Date | Fri, 18 Dec 2009 10:32:04 -0500 |
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Corrado Zoccolo <czoccolo@gmail.com> writes:
> Hi Jeff, > On Wed, Dec 9, 2009 at 7:09 PM, Jeff Moyer <jmoyer@redhat.com> wrote: >> Corrado Zoccolo <czoccolo@gmail.com> writes: >> >>> The numbers look good. Now, there is no penalty in having low_latency >>> set for sequential writes, and just a small penalty for random ones. >>> The fact that random reads are faster with low_latency set is interesting. >>> Is the test is running with your patched tiobench (so that the number >>> of random operations is comparable with sequential ones)? >> >> No, I forgot all about that. The number of random operations defaults >> to 4000, which is pretty low. I'll re-run the tests with a number >> comparable to the sequential runs. Sorry about that. >> > N.P. > if you have time, can you also re-run the test changing: > iosched/fifo_expire_async to 8 ? > I hope that reducing the expire_async, will make cfq quicker at switching > between the different threads, allowing more parallelism for seq > writers on your hw. > If this is the case, I think I can try to estimate the > fifo_expire_async in the autotuning patch.
Sorry this took so long. I've been rather busy of late.
Cheers, Jeff
low_latency=1, fifo_expire_async=8
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 ---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- ----- 2.6.32 8192 65536 8 88.39 89.74% 16.388 2032.62 0.00000 0.00000 98 2.6.32 8192 65536 16 90.77 185.3% 32.213 2175.99 0.00000 0.00000 49
Random Reads File Blk Num Avg Maximum Lat% Lat% CPU Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff ---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- ----- 2.6.32 8192 65536 8 19.62 25.74% 71.827 3397.26 0.00000 0.00000 76 2.6.32 8192 65536 16 23.82 55.01% 103.361 4075.53 0.00000 0.00000 43
Sequential Writes File Blk Num Avg Maximum Lat% Lat% CPU Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff ---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- ----- 2.6.32 8192 65536 8 108.28 1007.% 12.984 5643.55 0.00076 0.00000 11 2.6.32 8192 65536 16 112.40 2014.% 25.430 8592.98 0.00839 0.00000 6
Random Writes File Blk Num Avg Maximum Lat% Lat% CPU Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff ---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- ----- 2.6.32 8192 65536 8 63.94 337.7% 22.885 6047.22 0.00076 0.00000 19 2.6.32 8192 65536 16 61.94 662.5% 46.997 12759.69 0.15411 0.00000 9
low_latency=0, fifo_expire_async=8
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 ---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- ----- 2.6.32 8192 65536 8 89.13 88.30% 15.872 3101.39 0.00000 0.00000 101 2.6.32 8192 65536 16 86.78 161.7% 30.794 4909.02 0.00000 0.00000 54
Random Reads File Blk Num Avg Maximum Lat% Lat% CPU Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff ---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- ----- 2.6.32 8192 65536 8 20.21 26.64% 69.863 4285.42 0.00000 0.00000 76 2.6.32 8192 65536 16 20.10 52.75% 139.761 5986.94 0.00076 0.00000 38
Sequential Writes File Blk Num Avg Maximum Lat% Lat% CPU Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff ---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- ----- 2.6.32 8192 65536 8 108.74 1020.% 13.070 5331.78 0.00076 0.00000 11 2.6.32 8192 65536 16 112.18 2020.% 25.559 7903.16 0.00992 0.00000 6
Random Writes File Blk Num Avg Maximum Lat% Lat% CPU Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff ---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- ----- 2.6.32 8192 65536 8 64.53 337.8% 22.671 5388.77 0.00000 0.00000 19 2.6.32 8192 65536 16 61.75 668.9% 47.265 13271.37 0.12894 0.00000 9 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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