From: Andrew Morton <akpm@osdl.org>
To: William Lee Irwin III <wli@holomorphy.com>
Cc: devenyga@mcmaster.ca, ck@vds.kolivas.org, linux-kernel@vger.kernel.org
Subject: Re: [ck] Re: Preempt Threshold Measurements
Date: Mon, 12 Jul 2004 21:07:01 -0700 [thread overview]
Message-ID: <20040712210701.46e2cd40.akpm@osdl.org> (raw)
In-Reply-To: <20040713025502.GR21066@holomorphy.com>
William Lee Irwin III <wli@holomorphy.com> wrote:
>
> On Mon, Jul 12, 2004 at 10:48:50PM -0400, Gabriel Devenyi wrote:
> > Well I'm not particularly educated in kernel internals yet, here's some
> > reports from the system when its running.
> > 6ms non-preemptible critical section violated 4 ms preempt threshold starting
> > at do_munmap+0xd2/0x140 and ending at do_munmap+0xeb/0x140
> > [<c014007b>] do_munmap+0xeb/0x140
> > [<c01163b0>] dec_preempt_count+0x110/0x120
> > [<c014007b>] do_munmap+0xeb/0x140
> > [<c014010f>] sys_munmap+0x3f/0x60
> > [<c0103ee1>] sysenter_past_esp+0x52/0x71
>
> Looks like ZAP_BLOCK_SIZE may be too large for you. Lowering that some
> may "help" this. It's probably harmless, but try lowering that to half
> of whatever it is now, or maybe 64*PAGE_SIZE. It may be worthwhile
> to restructure how the preemption points are done in unmap_vmas() so
> we don't end up in some kind of tuning nightmare.
Does that instrumentation patch have the cond_resched_lock() fixups? If
not, this is a false positive.
The current setting of ZAP_BLOCK_SIZE is good for sub-500usec latencies on
a recentish CPU.
next prev parent reply other threads:[~2004-07-13 4:08 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-07-12 23:43 Preempt Threshold Measurements Gabriel Devenyi
2004-07-12 23:59 ` Con Kolivas
2004-07-13 0:15 ` Gabriel Devenyi
2004-07-13 2:40 ` William Lee Irwin III
2004-07-13 2:48 ` [ck] " Gabriel Devenyi
2004-07-13 2:54 ` Con Kolivas
2004-07-13 4:01 ` Andrew Morton
2004-07-13 5:51 ` Con Kolivas
2004-07-13 6:14 ` Andrew Morton
2004-07-13 8:03 ` Lee Revell
2004-07-13 10:26 ` Con Kolivas
2004-07-13 21:52 ` Con Kolivas
2004-07-13 10:08 ` William Lee Irwin III
2004-07-13 10:40 ` William Lee Irwin III
2004-07-13 11:07 ` Lenar Lõhmus
2004-07-13 11:13 ` William Lee Irwin III
2004-07-13 2:55 ` [ck] " William Lee Irwin III
2004-07-13 3:09 ` Gabriel Devenyi
2004-07-13 4:07 ` Andrew Morton [this message]
2004-07-13 5:34 ` Con Kolivas
2004-07-13 5:48 ` Nick Piggin
2004-07-13 10:14 ` William Lee Irwin III
2004-07-14 10:15 ` [ck] " Jens Bergmann
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