Messages in this thread | | | From | Jeff Moyer <> | Subject | Re: [PATCH] cfq-iosched: reduce write depth only if sync was delayed | Date | Fri, 11 Dec 2009 12:50:42 -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.
low_latency=1
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 19.35 26.10% 74.639 3278.74 0.00000 0.00000 74 2.6.32 8192 65536 16 20.40 53.07% 135.695 3705.55 0.00000 0.00000 38
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 64.64 342.2% 22.708 5960.22 0.00153 0.00000 19 2.6.32 8192 65536 16 61.19 663.7% 47.648 11294.56 0.16098 0.00000 9
low_latency=0
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 19.71 25.32% 70.891 4340.92 0.00000 0.00000 78 2.6.32 8192 65536 16 22.67 58.94% 121.669 6180.49 0.00229 0.00000 38
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 64.69 339.5% 22.651 6770.99 0.00152 0.00000 19 2.6.32 8192 65536 16 61.94 663.0% 46.962 10719.13 0.12741 0.00000 9
> if you have time, can you also re-run the test changing: > iosched/fifo_expire_async to 8 ?
Sure.
Cheers, Jeff -- 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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