Date: Mon, 26 Dec 2005 03:11:28 -0800
From: Andrew Morton <akpm@osdl.org>
To: Arjan van de Ven <arjan@infradead.org>
Cc: mingo@elte.hu, zippel@linux-m68k.org, hch@infradead.org,
       alan@lxorguk.ukuu.org.uk, linux-kernel@vger.kernel.org,
       torvalds@osdl.org, arjanv@infradead.org, nico@cam.org,
       jes@trained-monkey.org, zwane@arm.linux.org.uk, oleg@tv-sign.ru,
       dhowells@redhat.com, bcrl@kvack.org, rostedt@goodmis.org, ak@suse.de,
       rmk+lkml@arm.linux.org.uk
Subject: Re: [patch 0/9] mutex subsystem, -V4
Message-Id: <20051226031128.13bbace9.akpm@osdl.org>
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Arjan van de Ven <arjan@infradead.org> wrote:
>
> 
> > hm.  16 CPUs hitting the same semaphore at great arrival rates.  The cost
> > of a short spin is much less than the cost of a sleep/wakeup.  The machine
> > was doing 100,000 - 200,000 context switches per second.
> 
> interesting.. this might be a good indication that a "spin a bit first"
> mutex slowpath for some locks might be worth implementing...

If we see a workload which is triggering such high context switch rates,
maybe.  But I don't think we've seen any such for a long time.

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