From: Adrian Cox <adrian@humboldt.co.uk>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: Worst case performance of up()
Date: Sat, 02 Dec 2006 11:54:44 +0000 [thread overview]
Message-ID: <1165060484.4380.18.camel@localhost.localdomain> (raw)
In-Reply-To: <1165058151.22108.31.camel@localhost.localdomain>
On Sat, 2006-12-02 at 22:15 +1100, Benjamin Herrenschmidt wrote:
> I think we are hitting a livelock due to both CPUs trying to perform an
> atomic operation on the same cache line (or same variable even).
I agree.
> Can you remind me what CPU this on precisely ? I know that for some
> CPUs like 970's, Apple code has some weirdo workarounds around atomic
> ops involving forcing a mispredict when the stwcx. fails ... but if both
> CPUs are following the exact same pattern, I can't see another way out
> but an interrupt, unless something in the bus protocol can prevent such
> livelocks...
It's a pair of 7448s in MPX bus mode, with a Tsi109 host bridge.
--
Adrian Cox <adrian@humboldt.co.uk>
next prev parent reply other threads:[~2006-12-02 11:54 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-24 16:21 Worst case performance of up() Adrian Cox
2006-11-24 20:45 ` Benjamin Herrenschmidt
2006-11-27 21:02 ` Adrian Cox
2006-12-02 10:35 ` Adrian Cox
2006-12-02 11:15 ` Benjamin Herrenschmidt
2006-12-02 11:54 ` Adrian Cox [this message]
2006-12-02 20:52 ` Benjamin Herrenschmidt
2006-12-04 13:43 ` Adrian Cox
2006-12-04 20:25 ` Benjamin Herrenschmidt
2006-12-05 22:00 ` Benjamin Herrenschmidt
2006-12-08 2:33 ` Paul Mackerras
2006-12-08 3:10 ` Benjamin Herrenschmidt
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