Messages in this thread | | | Subject | Re: aim7 scalability issue on 4 socket machine | From | "Zhang, Yanmin" <> | Date | Fri, 18 Sep 2009 11:17:57 +0800 |
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On Thu, 2009-09-17 at 19:59 -0700, Andrew Morton wrote: > On Fri, 18 Sep 2009 10:02:19 +0800 "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> wrote: > > > > > Did you see Lee's patch?: > > > > > > > > http://lkml.org/lkml/2009/9/9/290 > > > > > > > > Added Lee and Hugh to CC, retained the below patch for them. > > > > > > Thanks a lot for the CC, Peter. > > > See my reply to that mail for the slightly corrected version. > > > > > > Yes, Yanmin and Lee appear to be fixing exactly the same issue. > > > I haven't thought through Yanmin's version for correctness, but > > > it lacks the vm_start check I added to Lee's, and I do prefer > > > Lee's style - hey, nothing personal! > > > > > > So, Yanmin, please retest with http://lkml.org/lkml/2009/9/13/25 > > > and let us know if that works as well for you - thanks. > > I tested Lee's patch and it does fix the issue. > > Do we think we should cook up something for -stable? It's better to have a patch for -stable.
> > Either this is a regression or the workload is particularly obscure. This issue is not clear on dual socket Nehalem machine (2*4*2 cpu), but is severe on large machine (4*8*2 cpu).
> > aim7 is sufficiently non-obscure to make me wonder what's happened here? I copy previous content below:
Aim7 consists of lots of subtests. One test is to fork lots of processes and every process calls sbrk for 1000 times to grow/shrink the heap. All the vma of the heap of all sub-processes point to the same anon_vma and use the same anon_vma->lock. When sbrk is called, kernel calls do_brk => vma_merge =>vma_adjust and lock anon_vma->lock to create spinlock contentions.
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