* [BENCHMARK] 2.5.39-mm1 @ 2002-09-30 9:41 Con Kolivas 2002-09-30 19:36 ` Andrew Morton 0 siblings, 1 reply; 11+ messages in thread From: Con Kolivas @ 2002-09-30 9:41 UTC (permalink / raw) To: linux-kernel; +Cc: Andrew Morton -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Here follow the contest v0.41 (http://contest.kolivas.net) results for 2.5.39-mm1: noload: Kernel Time CPU Ratio 2.4.19 67.71 98% 1.00 2.5.38 72.38 94% 1.07 2.5.38-mm3 73.00 93% 1.08 2.5.39 73.17 93% 1.08 2.5.39-mm1 72.97 94% 1.08 process_load: Kernel Time CPU Ratio 2.4.19 110.75 57% 1.64 2.5.38 85.71 79% 1.27 2.5.38-mm3 96.32 72% 1.42 2.5.39 88.9 75% 1.33* 2.5.39-mm1 99.0 69% 1.45* io_load: Kernel Time CPU Ratio 2.4.19 216.05 33% 3.19 2.5.38 887.76 8% 13.11 2.5.38-mm3 105.17 70% 1.55 2.5.39 229.4 34% 3.4 2.5.39-mm1 239.5 33% 3.4 mem_load: Kernel Time CPU Ratio 2.4.19 105.40 70% 1.56 2.5.38 107.89 73% 1.59 2.5.38-mm3 117.09 63% 1.73 2.5.39 103.72 72% 1.53 2.5.39-mm1 104.61 73% 1.54 process_load and io_load results are averages of 6 runs. Statistical significance in process_load performance (p=0.017), with mm1 slower. The other changes did not show statistical significance, with trends as noted above. note: these were done with the temporary fix for the reiserfs breakage but as far as I'm aware it shouldn't affect this test Hardware: 1133MhzP3, 224Mb Ram, IDE-ATA100 5400rpm drive with io_load tested on same disk, reiserFS. Preempt=N for all kernels. Con -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.7 (GNU/Linux) iD8DBQE9mBxUF6dfvkL3i1gRAr4kAJ47cICW0qIXLmswyBL9t1ZsiyxgVwCfaHCN bXOSrZtwTjJsSibiBm5KrRo= =XWpt -----END PGP SIGNATURE----- ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [BENCHMARK] 2.5.39-mm1 2002-09-30 9:41 [BENCHMARK] 2.5.39-mm1 Con Kolivas @ 2002-09-30 19:36 ` Andrew Morton 2002-09-30 20:36 ` Con Kolivas 2002-10-01 10:15 ` Jens Axboe 0 siblings, 2 replies; 11+ messages in thread From: Andrew Morton @ 2002-09-30 19:36 UTC (permalink / raw) To: Con Kolivas; +Cc: linux-kernel Con Kolivas wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Here follow the contest v0.41 (http://contest.kolivas.net) results for > 2.5.39-mm1: > > noload: > Kernel Time CPU Ratio > 2.4.19 67.71 98% 1.00 > 2.5.38 72.38 94% 1.07 > 2.5.38-mm3 73.00 93% 1.08 > 2.5.39 73.17 93% 1.08 > 2.5.39-mm1 72.97 94% 1.08 2.4.19 achieves higher CPU occupancy - you're using `make -j4', so it could be a CPU scheduler artifact, or a disk readahead latency effect. Is the kernel source in-cache for these runs? > process_load: > Kernel Time CPU Ratio > 2.4.19 110.75 57% 1.64 > 2.5.38 85.71 79% 1.27 > 2.5.38-mm3 96.32 72% 1.42 > 2.5.39 88.9 75% 1.33* > 2.5.39-mm1 99.0 69% 1.45* Not sure what to make of this test. We have a bunch of tasks sending data between each other across pipes while trying to build a kernel. It could be that with 2.4.19, those piping processes got a lot more work done. I'd be inclined to drop this test; not sure what it means. > io_load: > Kernel Time CPU Ratio > 2.4.19 216.05 33% 3.19 > 2.5.38 887.76 8% 13.11 > 2.5.38-mm3 105.17 70% 1.55 > 2.5.39 229.4 34% 3.4 > 2.5.39-mm1 239.5 33% 3.4 I think I'll set fifo_batch to 16 again... ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [BENCHMARK] 2.5.39-mm1 2002-09-30 19:36 ` Andrew Morton @ 2002-09-30 20:36 ` Con Kolivas 2002-10-01 10:16 ` Jens Axboe 2002-10-01 10:15 ` Jens Axboe 1 sibling, 1 reply; 11+ messages in thread From: Con Kolivas @ 2002-09-30 20:36 UTC (permalink / raw) To: Andrew Morton; +Cc: linux-kernel Quoting Andrew Morton <akpm@digeo.com>: > Con Kolivas wrote: > > > > -----BEGIN PGP SIGNED MESSAGE----- > > Hash: SHA1 > > > > Here follow the contest v0.41 (http://contest.kolivas.net) results for > > 2.5.39-mm1: > > > > noload: > > Kernel Time CPU Ratio > > 2.4.19 67.71 98% 1.00 > > 2.5.38 72.38 94% 1.07 > > 2.5.38-mm3 73.00 93% 1.08 > > 2.5.39 73.17 93% 1.08 > > 2.5.39-mm1 72.97 94% 1.08 > > 2.4.19 achieves higher CPU occupancy - you're using `make -j4', so it > could be a CPU scheduler artifact, or a disk readahead latency effect. > > Is the kernel source in-cache for these runs? Not cached. Swap should be empty and caches flushed prior to every load test. > > > process_load: > > Kernel Time CPU Ratio > > 2.4.19 110.75 57% 1.64 > > 2.5.38 85.71 79% 1.27 > > 2.5.38-mm3 96.32 72% 1.42 > > 2.5.39 88.9 75% 1.33* > > 2.5.39-mm1 99.0 69% 1.45* > > Not sure what to make of this test. We have a bunch of tasks > sending data between each other across pipes while trying to > build a kernel. > > It could be that with 2.4.19, those piping processes got a lot > more work done. > > I'd be inclined to drop this test; not sure what it means. Err yeah... > > > io_load: > > Kernel Time CPU Ratio > > 2.4.19 216.05 33% 3.19 > > 2.5.38 887.76 8% 13.11 > > 2.5.38-mm3 105.17 70% 1.55 > > 2.5.39 229.4 34% 3.4 > > 2.5.39-mm1 239.5 33% 3.4 > > I think I'll set fifo_batch to 16 again... > And I'll happily benchmark it when you do. Con. ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [BENCHMARK] 2.5.39-mm1 2002-09-30 20:36 ` Con Kolivas @ 2002-10-01 10:16 ` Jens Axboe 0 siblings, 0 replies; 11+ messages in thread From: Jens Axboe @ 2002-10-01 10:16 UTC (permalink / raw) To: Con Kolivas; +Cc: Andrew Morton, linux-kernel On Tue, Oct 01 2002, Con Kolivas wrote: > > > io_load: > > > Kernel Time CPU Ratio > > > 2.4.19 216.05 33% 3.19 > > > 2.5.38 887.76 8% 13.11 > > > 2.5.38-mm3 105.17 70% 1.55 > > > 2.5.39 229.4 34% 3.4 > > > 2.5.39-mm1 239.5 33% 3.4 > > > > I think I'll set fifo_batch to 16 again... > > > > And I'll happily benchmark it when you do. Just take 2.5.39-mm1 sources, edit drivers/block/deadline-iosched.c and set static int fifo_batch = 16; instead of the 32. -mm has them in sysctl too, iirc. -- Jens Axboe ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [BENCHMARK] 2.5.39-mm1 2002-09-30 19:36 ` Andrew Morton 2002-09-30 20:36 ` Con Kolivas @ 2002-10-01 10:15 ` Jens Axboe [not found] ` <3D9976D9.C06466B@digeo.com> [not found] ` <5.1.0.14.2.20021001190123.00b3cdc8@pop.gmx.net> 1 sibling, 2 replies; 11+ messages in thread From: Jens Axboe @ 2002-10-01 10:15 UTC (permalink / raw) To: Andrew Morton; +Cc: Con Kolivas, linux-kernel On Mon, Sep 30 2002, Andrew Morton wrote: > > io_load: > > Kernel Time CPU Ratio > > 2.4.19 216.05 33% 3.19 > > 2.5.38 887.76 8% 13.11 > > 2.5.38-mm3 105.17 70% 1.55 > > 2.5.39 229.4 34% 3.4 > > 2.5.39-mm1 239.5 33% 3.4 > > I think I'll set fifo_batch to 16 again... As not to compare oranges and apples, I'd very much like to see a 2.5.39-mm1 vs 2.5.39-mm1 with fifo_batch=16. Con, would you do that? Thanks! -- Jens Axboe ^ permalink raw reply [flat|nested] 11+ messages in thread
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* Re: [BENCHMARK] 2.5.39-mm1 [not found] ` <3D9976D9.C06466B@digeo.com> @ 2002-10-01 12:19 ` Con Kolivas 2002-10-01 12:30 ` Jens Axboe 0 siblings, 1 reply; 11+ messages in thread From: Con Kolivas @ 2002-10-01 12:19 UTC (permalink / raw) To: Andrew Morton, Jens Axboe; +Cc: linux kernel mailing list -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Tuesday 01 Oct 2002 8:20 pm, Andrew Morton wrote: > Jens Axboe wrote: > > On Mon, Sep 30 2002, Andrew Morton wrote: > > > > io_load: > > > > Kernel Time CPU Ratio > > > > 2.4.19 216.05 33% 3.19 > > > > 2.5.38 887.76 8% 13.11 > > > > 2.5.38-mm3 105.17 70% 1.55 > > > > 2.5.39 229.4 34% 3.4 > > > > 2.5.39-mm1 239.5 33% 3.4 > > > > > > I think I'll set fifo_batch to 16 again... > > > > As not to compare oranges and apples, I'd very much like to see a > > 2.5.39-mm1 vs 2.5.39-mm1 with fifo_batch=16. Con, would you do that? > > Thanks! > > The presence of /proc/sys/vm/fifo_batch should make that pretty easy. Thanks. That made it a lot easier and faster, and made me curious enough to create a family or very interesting results. All these are with 2.5.39-mm1 with fifo_batch set to 1->16, average of three runs. The first result is the unmodified 2.5.39-mm1 (fifo_batch=32). io_load: Kernel Time CPU% Ratio 2.5.39-mm1 239.5 32 3.54 2539mm1fb16 131.2 57 1.94 2539mm1fb8 109.1 68 1.61 2539mm1fb4 146.4 51 2.16 2539mm1fb2 112.7 65 1.67 2539mm1fb1 125.4 60 1.85 What's most interesting is the variation was small until the number was <8; then the variation between runs increased. Dare I say it there appears to be a sweet spot in the results. Con -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.7 (GNU/Linux) iD8DBQE9mZLPF6dfvkL3i1gRAjYnAKCGvWq43uTeClFz2tb6d8fcVe95zwCfbor2 HKO0FgK8kVsEvyQ3FwYaubg= =bAzC -----END PGP SIGNATURE----- ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [BENCHMARK] 2.5.39-mm1 2002-10-01 12:19 ` Con Kolivas @ 2002-10-01 12:30 ` Jens Axboe 2002-10-01 13:44 ` Con Kolivas 0 siblings, 1 reply; 11+ messages in thread From: Jens Axboe @ 2002-10-01 12:30 UTC (permalink / raw) To: Con Kolivas; +Cc: Andrew Morton, linux kernel mailing list On Tue, Oct 01 2002, Con Kolivas wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On Tuesday 01 Oct 2002 8:20 pm, Andrew Morton wrote: > > Jens Axboe wrote: > > > On Mon, Sep 30 2002, Andrew Morton wrote: > > > > > io_load: > > > > > Kernel Time CPU Ratio > > > > > 2.4.19 216.05 33% 3.19 > > > > > 2.5.38 887.76 8% 13.11 > > > > > 2.5.38-mm3 105.17 70% 1.55 > > > > > 2.5.39 229.4 34% 3.4 > > > > > 2.5.39-mm1 239.5 33% 3.4 > > > > > > > > I think I'll set fifo_batch to 16 again... > > > > > > As not to compare oranges and apples, I'd very much like to see a > > > 2.5.39-mm1 vs 2.5.39-mm1 with fifo_batch=16. Con, would you do that? > > > Thanks! > > > > The presence of /proc/sys/vm/fifo_batch should make that pretty easy. > > Thanks. That made it a lot easier and faster, and made me curious enough to > create a family or very interesting results. All these are with 2.5.39-mm1 > with fifo_batch set to 1->16, average of three runs. The first result is the > unmodified 2.5.39-mm1 (fifo_batch=32). Ah excellent, thanks a lot! > io_load: > Kernel Time CPU% Ratio > 2.5.39-mm1 239.5 32 3.54 > 2539mm1fb16 131.2 57 1.94 > 2539mm1fb8 109.1 68 1.61 > 2539mm1fb4 146.4 51 2.16 > 2539mm1fb2 112.7 65 1.67 > 2539mm1fb1 125.4 60 1.85 > > What's most interesting is the variation was small until the number was <8; > then the variation between runs increased. Dare I say it there appears to be > a sweet spot in the results. Yes it's an interesting curve. What makes it interesting is that 8 is better than 16. Both allow one seek to be dispatched, they only differ in the streamed amount of data we allow to dispatch. 8 will give you either 1 seek, or 8*256 == 2048 sectors == 1MiB. 16 will give you 1 seek or 2MiB of streamed I/O. Tests with other io benchmarks need to be considered as well. And I need a bit of time to digest this :-). The 8 vs 16 numbers are not what I expected. But the deadline io scheduler looks damn good in this test, if I have to say so myself. -- Jens Axboe ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [BENCHMARK] 2.5.39-mm1 2002-10-01 12:30 ` Jens Axboe @ 2002-10-01 13:44 ` Con Kolivas 2002-10-01 15:49 ` Jens Axboe 0 siblings, 1 reply; 11+ messages in thread From: Con Kolivas @ 2002-10-01 13:44 UTC (permalink / raw) To: Jens Axboe; +Cc: linux kernel mailing list -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Tuesday 01 Oct 2002 10:30 pm, Jens Axboe wrote: > On Tue, Oct 01 2002, Con Kolivas wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > > Hash: SHA1 > > > > On Tuesday 01 Oct 2002 8:20 pm, Andrew Morton wrote: > > > Jens Axboe wrote: > > > > On Mon, Sep 30 2002, Andrew Morton wrote: > > > > > > io_load: > > > > > > Kernel Time CPU Ratio > > > > > > 2.4.19 216.05 33% 3.19 > > > > > > 2.5.38 887.76 8% 13.11 > > > > > > 2.5.38-mm3 105.17 70% 1.55 > > > > > > 2.5.39 229.4 34% 3.4 > > > > > > 2.5.39-mm1 239.5 33% 3.4 > > > > > > > > > > I think I'll set fifo_batch to 16 again... > > > > > > > > As not to compare oranges and apples, I'd very much like to see a > > > > 2.5.39-mm1 vs 2.5.39-mm1 with fifo_batch=16. Con, would you do that? > > > > Thanks! > > > > > > The presence of /proc/sys/vm/fifo_batch should make that pretty easy. > > > > Thanks. That made it a lot easier and faster, and made me curious enough > > to create a family or very interesting results. All these are with > > 2.5.39-mm1 with fifo_batch set to 1->16, average of three runs. The first > > result is the unmodified 2.5.39-mm1 (fifo_batch=32). > > Ah excellent, thanks a lot! > > > io_load: > > Kernel Time CPU% Ratio > > 2.5.39-mm1 239.5 32 3.54 > > 2539mm1fb16 131.2 57 1.94 > > 2539mm1fb8 109.1 68 1.61 > > 2539mm1fb4 146.4 51 2.16 > > 2539mm1fb2 112.7 65 1.67 > > 2539mm1fb1 125.4 60 1.85 > > > > What's most interesting is the variation was small until the number was > > <8; then the variation between runs increased. Dare I say it there > > appears to be a sweet spot in the results. > > Yes it's an interesting curve. What makes it interesting is that 8 is > better than 16. Both allow one seek to be dispatched, they only differ > in the streamed amount of data we allow to dispatch. 8 will give you > either 1 seek, or 8*256 == 2048 sectors == 1MiB. 16 will give you 1 seek > or 2MiB of streamed I/O. > > Tests with other io benchmarks need to be considered as well. And I need > a bit of time to digest this :-). The 8 vs 16 numbers are not what I > expected. It would seem reasonable to me to assume it may be related to the filesystem in use (in this case ReiserFS). If this is the case it is possible that each different filesystem has a different sweetspot? (and for that matter each piece of hardware, each type of ata driver etc etc..) This was performed on an ATA100 5400rpm drive running ReiserFS. I'm afraid I don't have the hardware to do any other comparisons of different filesystems. > But the deadline io scheduler looks damn good in this test, if I have to > say so myself. Agree with you on that I can; Great job! Con -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.7 (GNU/Linux) iD8DBQE9maa1F6dfvkL3i1gRAqX5AKCdYYuzvqe57tB+EjzwO2WNo0ik6QCfU0RS 9bQXpIFvSgYb5WKk+6T2NUU= =Njny -----END PGP SIGNATURE----- ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [BENCHMARK] 2.5.39-mm1 2002-10-01 13:44 ` Con Kolivas @ 2002-10-01 15:49 ` Jens Axboe 2002-10-01 23:41 ` jw schultz 0 siblings, 1 reply; 11+ messages in thread From: Jens Axboe @ 2002-10-01 15:49 UTC (permalink / raw) To: Con Kolivas; +Cc: linux kernel mailing list On Tue, Oct 01 2002, Con Kolivas wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On Tuesday 01 Oct 2002 10:30 pm, Jens Axboe wrote: > > On Tue, Oct 01 2002, Con Kolivas wrote: > > > -----BEGIN PGP SIGNED MESSAGE----- > > > Hash: SHA1 > > > > > > On Tuesday 01 Oct 2002 8:20 pm, Andrew Morton wrote: > > > > Jens Axboe wrote: > > > > > On Mon, Sep 30 2002, Andrew Morton wrote: > > > > > > > io_load: > > > > > > > Kernel Time CPU Ratio > > > > > > > 2.4.19 216.05 33% 3.19 > > > > > > > 2.5.38 887.76 8% 13.11 > > > > > > > 2.5.38-mm3 105.17 70% 1.55 > > > > > > > 2.5.39 229.4 34% 3.4 > > > > > > > 2.5.39-mm1 239.5 33% 3.4 > > > > > > > > > > > > I think I'll set fifo_batch to 16 again... > > > > > > > > > > As not to compare oranges and apples, I'd very much like to see a > > > > > 2.5.39-mm1 vs 2.5.39-mm1 with fifo_batch=16. Con, would you do that? > > > > > Thanks! > > > > > > > > The presence of /proc/sys/vm/fifo_batch should make that pretty easy. > > > > > > Thanks. That made it a lot easier and faster, and made me curious enough > > > to create a family or very interesting results. All these are with > > > 2.5.39-mm1 with fifo_batch set to 1->16, average of three runs. The first > > > result is the unmodified 2.5.39-mm1 (fifo_batch=32). > > > > Ah excellent, thanks a lot! > > > > > io_load: > > > Kernel Time CPU% Ratio > > > 2.5.39-mm1 239.5 32 3.54 > > > 2539mm1fb16 131.2 57 1.94 > > > 2539mm1fb8 109.1 68 1.61 > > > 2539mm1fb4 146.4 51 2.16 > > > 2539mm1fb2 112.7 65 1.67 > > > 2539mm1fb1 125.4 60 1.85 > > > > > > What's most interesting is the variation was small until the number was > > > <8; then the variation between runs increased. Dare I say it there > > > appears to be a sweet spot in the results. > > > > Yes it's an interesting curve. What makes it interesting is that 8 is > > better than 16. Both allow one seek to be dispatched, they only differ > > in the streamed amount of data we allow to dispatch. 8 will give you > > either 1 seek, or 8*256 == 2048 sectors == 1MiB. 16 will give you 1 seek > > or 2MiB of streamed I/O. > > > > Tests with other io benchmarks need to be considered as well. And I need > > a bit of time to digest this :-). The 8 vs 16 numbers are not what I > > expected. > > It would seem reasonable to me to assume it may be related to the filesystem > in use (in this case ReiserFS). If this is the case it is possible that each > different filesystem has a different sweetspot? (and for that matter each > piece of hardware, each type of ata driver etc etc..) > > This was performed on an ATA100 5400rpm drive running ReiserFS. I'm afraid I > don't have the hardware to do any other comparisons of different filesystems. 8 being better than 16 would seem to indicate a slower driver, which fits with what you have. The sweet spot for this particular benchmark may be 8, that may not be the sweet spot for some other benchmark though. 16 will perhaps make a good default, we shall see once more benchmarks are done. I think you'll find that results will be similar on other file systems, the io scheduler settings will be more affected by the underlying hardware. -- Jens Axboe ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [BENCHMARK] 2.5.39-mm1 2002-10-01 15:49 ` Jens Axboe @ 2002-10-01 23:41 ` jw schultz 0 siblings, 0 replies; 11+ messages in thread From: jw schultz @ 2002-10-01 23:41 UTC (permalink / raw) To: linux kernel mailing list On Tue, Oct 01, 2002 at 05:49:28PM +0200, Jens Axboe wrote: > On Tue, Oct 01 2002, Con Kolivas wrote: > > On Tuesday 01 Oct 2002 10:30 pm, Jens Axboe wrote: > > > On Tue, Oct 01 2002, Con Kolivas wrote: > > > > On Tuesday 01 Oct 2002 8:20 pm, Andrew Morton wrote: > > > > > Jens Axboe wrote: > > > > > > On Mon, Sep 30 2002, Andrew Morton wrote: > > > > > > > > io_load: > > > > > > > > Kernel Time CPU Ratio > > > > > > > > 2.4.19 216.05 33% 3.19 > > > > > > > > 2.5.38 887.76 8% 13.11 > > > > > > > > 2.5.38-mm3 105.17 70% 1.55 > > > > > > > > 2.5.39 229.4 34% 3.4 > > > > > > > > 2.5.39-mm1 239.5 33% 3.4 > > > > > > > > > > > > > > I think I'll set fifo_batch to 16 again... > > > > > > > > > > > > As not to compare oranges and apples, I'd very much like to see a > > > > > > 2.5.39-mm1 vs 2.5.39-mm1 with fifo_batch=16. Con, would you do that? > > > > > > Thanks! > > > > > > > > > > The presence of /proc/sys/vm/fifo_batch should make that pretty easy. > > > > > > > > Thanks. That made it a lot easier and faster, and made me curious enough > > > > to create a family or very interesting results. All these are with > > > > 2.5.39-mm1 with fifo_batch set to 1->16, average of three runs. The first > > > > result is the unmodified 2.5.39-mm1 (fifo_batch=32). > > > > > > Ah excellent, thanks a lot! > > > > > > > io_load: > > > > Kernel Time CPU% Ratio > > > > 2.5.39-mm1 239.5 32 3.54 > > > > 2539mm1fb16 131.2 57 1.94 > > > > 2539mm1fb8 109.1 68 1.61 > > > > 2539mm1fb4 146.4 51 2.16 > > > > 2539mm1fb2 112.7 65 1.67 > > > > 2539mm1fb1 125.4 60 1.85 > > > > > > > > What's most interesting is the variation was small until the number was > > > > <8; then the variation between runs increased. Dare I say it there > > > > appears to be a sweet spot in the results. > > > > > > Yes it's an interesting curve. What makes it interesting is that 8 is > > > better than 16. Both allow one seek to be dispatched, they only differ > > > in the streamed amount of data we allow to dispatch. 8 will give you > > > either 1 seek, or 8*256 == 2048 sectors == 1MiB. 16 will give you 1 seek > > > or 2MiB of streamed I/O. > > > > > > Tests with other io benchmarks need to be considered as well. And I need > > > a bit of time to digest this :-). The 8 vs 16 numbers are not what I > > > expected. > > > > It would seem reasonable to me to assume it may be related to the filesystem > > in use (in this case ReiserFS). If this is the case it is possible that each > > different filesystem has a different sweetspot? (and for that matter each > > piece of hardware, each type of ata driver etc etc..) > > > > This was performed on an ATA100 5400rpm drive running ReiserFS. I'm afraid I > > don't have the hardware to do any other comparisons of different filesystems. > > 8 being better than 16 would seem to indicate a slower driver, which > fits with what you have. The sweet spot for this particular benchmark > may be 8, that may not be the sweet spot for some other benchmark > though. 16 will perhaps make a good default, we shall see once more > benchmarks are done. > > I think you'll find that results will be similar on other file systems, > the io scheduler settings will be more affected by the underlying > hardware. Just a thought but might the variability be due to physical cylinder boundaries? 1-2Mib is very close to cylider size. Getting down below that range and a significant number of requests might not cross boundaries affecting latency. Much larger requests and it will just be an issue of 1 boundary more or less. -- ________________________________________________________________ J.W. Schultz Pegasystems Technologies email address: jw@pegasys.ws Remember Cernan and Schmitt ^ permalink raw reply [flat|nested] 11+ messages in thread
[parent not found: <5.1.0.14.2.20021001190123.00b3cdc8@pop.gmx.net>]
[parent not found: <20021001172200.GH5755@suse.de>]
* Re: [BENCHMARK] 2.5.39-mm1 [not found] ` <20021001172200.GH5755@suse.de> @ 2002-10-02 2:55 ` Con Kolivas 0 siblings, 0 replies; 11+ messages in thread From: Con Kolivas @ 2002-10-02 2:55 UTC (permalink / raw) To: Jens Axboe; +Cc: Mike Galbraith, Andrew Morton, linux-kernel Quoting Jens Axboe <axboe@suse.de>: > On Tue, Oct 01 2002, Mike Galbraith wrote: > > At 10:19 PM 10/1/2002 +1000, Con Kolivas wrote: > > >On Tuesday 01 Oct 2002 8:20 pm, Andrew Morton wrote: > > >> Jens Axboe wrote: > > >> > On Mon, Sep 30 2002, Andrew Morton wrote: [snip] > > >> > > > > >> > > I think I'll set fifo_batch to 16 again... > > >> > > > >> > As not to compare oranges and apples, I'd very much like to see a > > >> > 2.5.39-mm1 vs 2.5.39-mm1 with fifo_batch=16. Con, would you do that? > > >> > Thanks! > > >> > > >> The presence of /proc/sys/vm/fifo_batch should make that pretty easy. > > > > > >Thanks. That made it a lot easier and faster, and made me curious enough > to > > >create a family or very interesting results. All these are with > 2.5.39-mm1 > > >with fifo_batch set to 1->16, average of three runs. The first result is [snip] > > >What's most interesting is the variation was small until the number was > <8; > > >then the variation between runs increased. Dare I say it there appears to > > > >be > > >a sweet spot in the results. > > > > What's more interesting (methinks) is the huge difference between 32 and > > 16. Have you played with values between 32 and 16? (/me wonders if > > there's a cliff or a gentle slope) > > As I wrote in response, the difference is that 16 == seek_cost. So > fifo_batch of 16 will allow 1 seek, fifo_batch of 32 will allow two. > This is the reason for the big drop at that point. I would expect 31 to > be pretty close to 16. Ok well I've got the answer to both questions. I've removed the other results from this email for clarity, and here is a more complete family (average of 2 or 3 runs): io_load: Kernel Time CPU% Ratio 2539mm1fb01 125.4 60 1.85 2539mm1fb02 112.7 65 1.66 2539mm1fb04 146.4 51 2.16 2539mm1fb08 109.1 68 1.61 2539mm1fb10 204.3 63 3.02 2539mm1fb12 210.3 60 3.10 2539mm1fb14 192.6 66 2.85 2539mm1fb16 131.2 57 1.94 2539mm1fb18 209.7 61 3.10 2539mm1fb20 221.8 57 3.27 2539mm1fb22 262.3 48 3.88 2539mm1fb24 264.0 48 3.90 2539mm1fb26 258.7 50 3.82 2539mm1fb28 307.4 42 4.54 2539mm1fb30 319.4 40 4.71 2539mm1fb31 294.4 44 4.34 2539mm1fb32 239.5 32 3.54 For my machine at least it appears that falling outside the powers of 2 is not good. Con ^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2002-10-02 2:50 UTC | newest]
Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
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2002-09-30 9:41 [BENCHMARK] 2.5.39-mm1 Con Kolivas
2002-09-30 19:36 ` Andrew Morton
2002-09-30 20:36 ` Con Kolivas
2002-10-01 10:16 ` Jens Axboe
2002-10-01 10:15 ` Jens Axboe
[not found] ` <3D9976D9.C06466B@digeo.com>
2002-10-01 12:19 ` Con Kolivas
2002-10-01 12:30 ` Jens Axboe
2002-10-01 13:44 ` Con Kolivas
2002-10-01 15:49 ` Jens Axboe
2002-10-01 23:41 ` jw schultz
[not found] ` <5.1.0.14.2.20021001190123.00b3cdc8@pop.gmx.net>
[not found] ` <20021001172200.GH5755@suse.de>
2002-10-02 2:55 ` Con Kolivas
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