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From: Roland McGrath <roland@redhat.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Jason Baron <jbaron@redhat.com>,
	linux-kernel@vger.kernel.org, mathieu.desnoyers@polymtl.ca,
	rth@redhat.com
Subject: Re: [PATCH 0/4] RFC: jump label - (tracepoint optimizations)
Date: Thu,  3 Sep 2009 14:11:42 -0700 (PDT)	[thread overview]
Message-ID: <20090903211142.8490C47C94@magilla.sf.frob.com> (raw)
In-Reply-To: Ingo Molnar's message of  Thursday, 3 September 2009 23:01:39 +0200 <20090903210139.GA25581@elte.hu>

> This looks really interesting and desired. Once GCC adds this (or an 
> equivalent) feature, i'd love to have your optimization in the 
> kernel.

We expect it will be in gcc 4.5 and backported to Fedora's 4.4 pretty soon.
But it's not finalized yet, so we are only doing proof-of-concept so far.

> Basically everything that is optional and touches some very hot 
> codepath would be eligible - not just tracepoints.

Sure.  Any place you have a load+conditional-jump where that is too costly,
we can make it a nop that costs a only cycle or so.  We probably want to
think a little harder about the nicest macro setup we can do to make
employing this trivial in the source.


Thanks,
Roland

  reply	other threads:[~2009-09-03 21:12 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-09-03 20:25 Jason Baron
2009-09-03 20:25 ` [PATCH 1/4] RFC: basic jump label implementation Jason Baron
2009-09-03 20:25 ` [PATCH 2/4] RFC: jump label example usage Jason Baron
2009-09-03 20:26 ` [PATCH 3/4] RFC: implement tracepoints on top of jump patching Jason Baron
2009-09-03 20:26 ` [PATCH 4/4] RFC: performance testing harness Jason Baron
2009-09-03 20:45 ` [PATCH 0/4] RFC: jump label - (tracepoint optimizations) Daniel Walker
2009-09-03 21:01 ` Ingo Molnar
2009-09-03 21:11   ` Roland McGrath [this message]
2009-09-07 15:48 ` Mathieu Desnoyers
2009-09-07 17:06   ` Mathieu Desnoyers
2009-09-10 21:15     ` Steven Rostedt
2009-09-08 20:48   ` Jason Baron

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