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From: Roland McGrath <roland@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Jason Baron <jbaron@redhat.com>,
	linux-kernel@vger.kernel.org, fweisbec@gmail.com, mingo@elte.hu,
	laijs@cn.fujitsu.com, rostedt@goodmis.org,
	mathieu.desnoyers@polymtl.ca, jiayingz@google.com,
	mbligh@google.com, fche@redhat.com
Subject: Re: [PATCH 0/3] tracepoints: delay argument evaluation
Date: Wed, 20 May 2009 02:18:17 -0700 (PDT)	[thread overview]
Message-ID: <20090520091817.8E3EEFC38D@magilla.sf.frob.com> (raw)
In-Reply-To: Peter Zijlstra's message of  Wednesday, 20 May 2009 09:38:47 +0200 <1242805127.26820.532.camel@twins>

> But I think we should be asking GCC to get fixed. Since inline functions
> don't act like a compiler barrier anyway, they might as well not force
> argument evaluation either.

I quite agree.  I'm all for better compilation.  However, usual practice
in the kernel has been to complain about introducing C code sequences
that add a few instructions when compiled by compilers over 5 years old,
let alone the very latest one.  I think it was the expectation of that
sort of sensitive reaction to the hot-path impact of unused tracepoints
that motivated Jason's attempt at microoptimization.


Thanks,
Roland

  reply	other threads:[~2009-05-20  9:19 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-05-19 21:03 Jason Baron
2009-05-19 21:03 ` [PATCH 1/3] tracepoints: add tracepoint_call() to optimize tracepoints disabled Jason Baron
2009-05-19 21:03 ` [PATCH 2/3] tracepoints: convert scheduler tracepoints to 'tracepoint_call' api Jason Baron
2009-05-19 21:03 ` [PATCH 3/3] tracepoints: convert block " Jason Baron
2009-05-19 21:17 ` [PATCH 0/3] tracepoints: delay argument evaluation Mathieu Desnoyers
2009-05-19 22:16   ` Jason Baron
2009-05-19 22:25     ` Roland McGrath
2009-05-19 22:31       ` Steven Rostedt
2009-05-19 22:36   ` Steven Rostedt
2009-05-19 23:52     ` Frederic Weisbecker
2009-05-20  0:33     ` Mathieu Desnoyers
2009-05-20  0:42       ` Steven Rostedt
2009-05-20  7:01       ` Roland McGrath
2009-05-20  7:12 ` Peter Zijlstra
     [not found]   ` <20090520072750.DA9A0FC38D@magilla.sf.frob.com>
2009-05-20  7:38     ` Peter Zijlstra
2009-05-20  9:18       ` Roland McGrath [this message]
2009-05-20  7:33 ` Ingo Molnar
2009-05-20 15:42   ` Jason Baron
2009-05-21  1:49     ` Jiaying Zhang
2009-05-21  1:59       ` Li Zefan
2009-05-21  2:15         ` Jiaying Zhang
2009-05-21  2:41           ` Li Zefan

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