From: Ingo Molnar <mingo@elte.hu>
To: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH tip/tracing/markers] new probes manager
Date: Mon, 27 Oct 2008 19:26:55 +0100 [thread overview]
Message-ID: <20081027182655.GA11494@elte.hu> (raw)
In-Reply-To: <20081027163046.GA20692@Krystal>
* Mathieu Desnoyers <compudj@krystal.dyndns.org> wrote:
> * Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca) wrote:
> > * Lai Jiangshan (laijs@cn.fujitsu.com) wrote:
> > >
> > > this patch use a new probes manager for marker.
> > >
> > > the most important benefit of this patch is:
> > > 1) smp_rmb() is removed from the critical path. as we know rmb()
> > > is very expensive.
> > >
> >
> > Do you have performance measurements for this ? On x86 it's a nop,
> > AFAIK.
>
> My statement above is inexact : x86_64 uses lfence for rmb(). But
> numbers would still be welcome.
yes, the statement that rmb() is very expensive looks dubious. It is
absolutely cheap everywhere.
Ingo
next prev parent reply other threads:[~2008-10-27 18:27 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-23 2:47 [PATCH tip/tracing/markers] new probes manager Lai Jiangshan
2008-10-27 15:58 ` Mathieu Desnoyers
2008-10-27 16:30 ` Mathieu Desnoyers
2008-10-27 18:26 ` Ingo Molnar [this message]
2008-10-27 23:13 ` Paul Mackerras
2008-10-28 1:17 ` Lai Jiangshan
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