Re: 4BSD/ULE numbers...

From: Peter Jeremy (PeterJeremy_at_optushome.com.au)
Date: 09/27/05

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    Date: Tue, 27 Sep 2005 19:17:49 +1000
To: Kris Kennaway <kris@obsecurity.org>

    On Mon, 2005-Sep-26 18:44:53 -0400, Kris Kennaway wrote:
    >I'd love a way to measure sched_lock contention..I'm sure it's a
    >factor on e.g. my machines with >=10 CPUs, but mutex profiling doesn't
    >see it because it's a spinlock.

    How about adding a spincount field in struct mtx and incrementing it in
    the inner loop of _mtx_lock_spin()? This wouldn't be perfect but you
    could get a rough idea of the lock contention by looking at the rate
    that the spincount field incremented.

    Working out how many CPUs are simultaneously contending for sched_lock
    would be more difficult but doable. 

    -- 
Peter Jeremy
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