From: John H. <ha...@en...> - 2001-03-17 02:48:56
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FYI: Some deprived users are unable to run AIM7 and reproduce my benchmark results reported earlier. [The AIM7 "shared use" workload (minus the sync_* subtests) scales well to about 4 cpus (4 cpus sees about 3.4x a single cpu), then flattens out above that due to contention on the global pagecache_lock (32 cpus sees about 6x a single cpu). The "pagecache_lock patch" (finer-grained locking) allows much improved scaling: 4 cpus sees about 3.9x a single cpu, peaking at 28 cpus at about 18x a single cpu).] I've attempted to reproduce this same scaling bottleneck with another test. I tried using the old standby: kernel make (where -jN optimally matches N cpus). Alas, when running on a mips64 system, building a mips64 kernel, this doesn't hammer at the pagecache_lock quite as much as AIM7. I see no real difference between 2.4.2 and 2.4.2+pcl ("pcl" is the "pagecache_lock patch") up to 16 cpus. At 24 cpus I observe a 20% improvement with the "pcl" patch. At 32 cpus I observe a 56% improvement. Thus, the "pcl" patch is still a big win, but the kernel make "benchmark" doesn't exhibit quite as dramatic proof of that as does AIM7. John Hawkes ha...@en... |
From: <JD...@de...> - 2001-03-19 14:21:42
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John Hawkes wrote: >> FYI: >> >> Some deprived users are unable to run AIM7 and reproduce my benchmar= k >> results reported earlier. >> >> [The AIM7 "shared use" workload (minus the sync_* subtests) scales w= ell >> to about 4 cpus (4 cpus sees about 3.4x a single cpu), then flattens= out >> above that due to contention on the global pagecache_lock (32 cpus s= ees >> about 6x a single cpu). The "pagecache_lock patch" (finer-grained >> locking) allows much improved scaling: 4 cpus sees about 3.9x a sin= gle >> cpu, peaking at 28 cpus at about 18x a single cpu).] >> >> I've attempted to reproduce this same scaling bottleneck with anothe= r >> test. I tried using the old standby: kernel make (where -jN optimal= ly >> matches N cpus). Alas, when running on a mips64 system, building a >> mips64 kernel, this doesn't hammer at the pagecache_lock quite as mu= ch >> as AIM7. I see no real difference between 2.4.2 and 2.4.2+pcl ("pcl= " is >> the "pagecache_lock patch") up to 16 cpus. At 24 cpus I observe a 2= 0% >> improvement with the "pcl" patch. At 32 cpus I observe a 56% >> improvement. Thus, the "pcl" patch is still a big win, but the kern= el >> make "benchmark" doesn't exhibit quite as dramatic proof of that as = does >> AIM7. >> >> John Hawkes >> ha...@en... Where can I get the pagecache_lock patch? Is it also available for 2.4.= 0 and what are the prerequisites? Juergen Doelle ______________________________________________________________ Dr. Juergen Doelle LINUX Architecture & Performance IBM Lab Boeblingen D-71032 B=F6blingen, Sch=F6naicher Stra=DFe 220 Phone: (49)-7031-16-4218, Internet: jd...@de... = |
From: Rajagopal A. <an...@sg...> - 2001-03-19 21:49:26
Attachments:
pcl-2.4.2.patch
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JD...@de... wrote: > > Where can I get the pagecache_lock patch? Is it also available for 2.4.0 > and what are the prerequisites? Here's a patch against 2.4.2 which I've tested against X86 & John Hawkes has tested against MIPS64. Shortly I'll respin the patch against 2.4.0, but that won't be tested ... I'd recommed you use the 2.4.2 version for a number of other reasons as well. Cheers, ananth. -------------------------------------------------------------------------- Rajagopal Ananthanarayanan ("ananth") Member Technical Staff, SGI. -------------------------------------------------------------------------- |
From: Rajagopal A. <an...@sg...> - 2001-03-19 21:54:25
Attachments:
pcl-2.4.0.patch
|
JD...@de... wrote: > > Where can I get the pagecache_lock patch? Is it also available for 2.4.0 > and what are the prerequisites? Ok, here's the untested pcl-2.4.0.patch ... only guarantee is that it compiles ;-) cheers, ananth. -------------------------------------------------------------------------- Rajagopal Ananthanarayanan ("ananth") Member Technical Staff, SGI. -------------------------------------------------------------------------- |