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From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: William Cohen <wcohen@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>, Ingo Molnar <mingo@elte.hu>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Add minimal support for software performance counters for ia64
Date: Wed, 19 Aug 2009 18:12:31 +0200	[thread overview]
Message-ID: <1250698351.8282.106.camel@twins> (raw)
In-Reply-To: <4A8C2290.3040707@redhat.com>

On Wed, 2009-08-19 at 12:04 -0400, William Cohen wrote:
> +#ifdef __ia64__
> +#include "../../arch/ia64/include/asm/unistd.h"
> +#define rmb()          asm volatile("" ::: "memory")
> +#define cpu_relax()    asm volatile("" ::: "memory");
> +#endif

Surely the itanic has a real memory barrier? The kernel seems to use
something along the lines of mf.

Also, cpu_relax() seems to end up being asm volatile("hint @pause" :::
"memory"), although we don't seem to have an actual user of cpu_relax()
in perf atm.




  reply	other threads:[~2009-08-19 16:12 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-08-19 16:04 [PATCH] Add minimal support for software performance counters for ia64 William Cohen
2009-08-19 16:12 ` Peter Zijlstra [this message]
2009-08-19 19:04   ` William Cohen
2009-08-19 19:06     ` Peter Zijlstra
2009-08-20 21:19       ` William Cohen
2009-08-21 14:25         ` Ingo Molnar
2009-08-21 15:09           ` William Cohen
2009-08-21 16:37             ` [PATCH, V2] perf_counter, IA64: Add support for software performance counters Ingo Molnar
2009-08-19 16:12 ` [PATCH] Add minimal " Ingo Molnar
2009-08-19 16:12   ` [PATCH] Add minimal support for software performance counters for ia64 Ingo Molnar

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