Re: [ck] Re: Preempt Threshold Measurements

[William Lee Irwin III]

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.


-- wli
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