From: Nick Piggin <npiggin@suse.de>
To: Anton Blanchard <anton@samba.org>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: [PATCH 6/6] powerpc: Use lwsync for acquire barrier if CPU supports it
Date: Thu, 11 Feb 2010 18:09:14 +1100 [thread overview]
Message-ID: <20100211070914.GB6735@laptop> (raw)
In-Reply-To: <20100210111025.GF3399@kryten>
On Wed, Feb 10, 2010 at 10:10:25PM +1100, Anton Blanchard wrote:
>
> Nick Piggin discovered that lwsync barriers around locks were faster than isync
> on 970. That was a long time ago and I completely dropped the ball in testing
> his patches across other ppc64 processors.
>
> Turns out the idea helps on other chips. Using a microbenchmark that
> uses a lot of threads to contend on a global pthread mutex (and therefore a
> global futex), POWER6 improves 8% and POWER7 improves 2%. I checked POWER5
> and while I couldn't measure an improvement, there was no regression.
Ah, good to see this one come back. I also tested tbench over localhost
btw which actually did show some speedup on the G5.
BTW. this was the last thing left:
http://www.mail-archive.com/linuxppc-dev@lists.ozlabs.org/msg29738.html
Don't know if you took a look at that again, but maybe it's worth
looking at. Hmm, we do actually seem to be growing number of smp_mb*
calls in core kernel too.
next prev parent reply other threads:[~2010-02-11 7:09 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-10 10:57 [PATCH 1/6] powerpc: Use lwarx hint in spinlocks Anton Blanchard
2010-02-10 11:02 ` [PATCH 2/6] powerpc: Use lwarx/ldarx hint in bit locks Anton Blanchard
2010-02-10 11:03 ` [PATCH 3/6] powerpc: Convert open coded native hashtable bit lock Anton Blanchard
2010-02-10 11:04 ` [PATCH 4/6] powerpc: Rename LWSYNC_ON_SMP to PPC_RELEASE_BARRIER, ISYNC_ON_SMP to PPC_ACQUIRE_BARRIER Anton Blanchard
2010-02-10 11:07 ` [PATCH 5/6] powerpc: Fix lwsync patching code on 64bit Anton Blanchard
2010-02-10 11:10 ` [PATCH 6/6] powerpc: Use lwsync for acquire barrier if CPU supports it Anton Blanchard
2010-02-11 7:09 ` Nick Piggin [this message]
2010-02-17 9:43 ` Anton Blanchard
2010-02-17 10:41 ` Nick Piggin
2010-02-17 12:12 ` Benjamin Herrenschmidt
2010-02-16 4:22 ` Olof Johansson
2010-02-16 4:19 ` Benjamin Herrenschmidt
2010-02-16 6:07 ` Olof Johansson
2010-03-19 1:08 ` [PATCH 4/6] powerpc: Rename LWSYNC_ON_SMP to PPC_RELEASE_BARRIER, ISYNC_ON_SMP to PPC_ACQUIRE_BARRIER Nick Piggin
2010-03-19 1:36 ` Benjamin Herrenschmidt
2010-02-11 6:56 ` [PATCH 1/6] powerpc: Use lwarx hint in spinlocks Nick Piggin
2010-02-17 9:37 ` Anton Blanchard
2010-02-17 10:22 ` Nick Piggin
2010-02-16 4:16 ` Olof Johansson
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