From: Linus Torvalds <torvalds@linux-foundation.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: Steven Rostedt <srostedt@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
Steven Rostedt <rostedt@goodmis.org>,
Jeremy Fitzhardinge <jeremy@goop.org>,
LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
David Miller <davem@davemloft.net>,
Roland McGrath <roland@redhat.com>,
Ulrich Drepper <drepper@redhat.com>,
Rusty Russell <rusty@rustcorp.com.au>,
Gregory Haskins <ghaskins@novell.com>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
"Luis Claudio R. Goncalves" <lclaudio@uudg.org>,
Clark Williams <williams@redhat.com>
Subject: Re: Efficient x86 and x86_64 NOP microbenchmarks
Date: Wed, 13 Aug 2008 13:21:22 -0700 (PDT) [thread overview]
Message-ID: <alpine.LFD.1.10.0808131320000.3462@nehalem.linux-foundation.org> (raw)
In-Reply-To: <20080813201532.GR1366@one.firstfloor.org>
On Wed, 13 Aug 2008, Andi Kleen wrote:
>
> Also I must say the whole ftrace noping exercise is pretty pointless without
> avoiding frame pointers because it does save less than what you lose
> unconditionally from the "select FRAME_POINTER"
Andi, you seem to have missed the whole point. This is a _correctness_
issue as long as the nop is not a single instruction. And the workaround
for that is uglier than just making a single-instruction nop.
So the question now is to find a good nop that _is_ a single atomic
instruction. Your blathering about frame pointers is missing the whole
point!
Linus
next prev parent reply other threads:[~2008-08-13 20:22 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20080813191926.GB15547@Krystal>
2008-08-13 20:00 ` Steven Rostedt
2008-08-13 20:06 ` Jeremy Fitzhardinge
2008-08-13 20:34 ` Steven Rostedt
2008-08-13 20:15 ` Andi Kleen
2008-08-13 20:21 ` Linus Torvalds [this message]
2008-08-13 20:21 ` Steven Rostedt
2008-08-08 18:13 [PATCH 0/5] ftrace: to kill a daemon Steven Rostedt
2008-08-08 18:21 ` Mathieu Desnoyers
2008-08-08 18:41 ` Steven Rostedt
2008-08-08 19:05 ` Mathieu Desnoyers
2008-08-08 23:38 ` Steven Rostedt
2008-08-09 0:23 ` Andi Kleen
2008-08-09 0:36 ` Steven Rostedt
2008-08-09 0:47 ` Jeremy Fitzhardinge
2008-08-09 0:51 ` Linus Torvalds
2008-08-09 1:25 ` Steven Rostedt
2008-08-13 17:52 ` Efficient x86 and x86_64 NOP microbenchmarks Mathieu Desnoyers
2008-08-13 18:27 ` Linus Torvalds
2008-08-13 18:41 ` Andi Kleen
2008-08-13 18:45 ` Avi Kivity
2008-08-13 18:51 ` Andi Kleen
2008-08-13 18:56 ` Avi Kivity
2008-08-13 19:30 ` Mathieu Desnoyers
2008-08-13 19:37 ` Andi Kleen
2008-08-13 20:01 ` Mathieu Desnoyers
2008-08-15 21:34 ` Steven Rostedt
2008-08-15 21:51 ` Andi Kleen
2008-08-13 19:16 ` Mathieu Desnoyers
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