From: Peter Zijlstra <peterz@infradead.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>, "H. Peter Anvin" <hpa@zytor.com>,
Jason Baron <jbaron@redhat.com>,
mathieu.desnoyers@efficios.com, davem@davemloft.net,
ddaney.cavm@gmail.com, akpm@linux-foundation.org,
linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
rth <rth@redhat.com>
Subject: Re: [PATCH 00/10] jump label: introduce very_[un]likely + cleanups + docs
Date: Wed, 22 Feb 2012 16:32:32 +0100 [thread overview]
Message-ID: <1329924752.24994.25.camel@twins> (raw)
In-Reply-To: <1329923583.24994.21.camel@twins>
On Wed, 2012-02-22 at 16:13 +0100, Peter Zijlstra wrote:
> On Wed, 2012-02-22 at 08:54 -0500, Steven Rostedt wrote:
> > But we could push a "unlikely(static_branch())" for
> > such a case (or keep it as very_unlikely()).
>
> If only that would work.. GCC assumes a bunch of things when you use
> 'asm goto'. An unbiased 'asm goto' that would take likely() and
> unlikely() hints would be ideal, but alas that's not how the thing got
> implemented.
>
> Now arguable we could maybe just stick with the static_branch() thing
> and decide that GCC is broken for adding bias and not respecting
> likely() and unlikely(), but the GCC folks might have an opinion there.
>
> Anyway, if we have to stick with the current implementation then an
> unbiased version is impossible to implement.
>
> If we get GCC folks on board to change stuff, who knows.
So I clicked the link Jason provided in his 10/10 Documentation patch
and stumbled upon:
http://gcc.gnu.org/ml/gcc-patches/2009-07/msg01558.html
Where rth suggests that __attribute__((hot,cold)) might work on the
destination labels. Trying this my compiler (4.6.1+crap) pukes all over
me suggesting this isn't (yet) implemented.
Richard, is something like that still on the table?
next prev parent reply other threads:[~2012-02-22 15:32 UTC|newest]
Thread overview: 84+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-21 20:02 [PATCH 00/10] jump label: introduce very_[un]likely + cleanups + docs Jason Baron
2012-02-21 20:02 ` [PATCH 01/10] jump label: Add a WARN() if jump label key count goes negative Jason Baron
2012-02-29 10:13 ` [tip:perf/core] " tip-bot for Jason Baron
2012-02-21 20:02 ` [PATCH 02/10] jump label: fix compiler warning Jason Baron
2012-02-29 10:14 ` [tip:perf/core] jump label: Fix " tip-bot for Jason Baron
2012-02-21 20:03 ` [PATCH 03/10] jump label: introduce very_unlikely() Jason Baron
2012-02-21 20:03 ` [PATCH 04/10] jump label: introduce very_likely() Jason Baron
2012-02-21 20:03 ` [PATCH 05/10] perf: update to use 'very_unlikely()' Jason Baron
2012-02-21 20:03 ` [PATCH 06/10] tracepoints: update to use very_unlikely() Jason Baron
2012-02-21 20:03 ` [PATCH 07/10] sched: update to use very_[un]likely() Jason Baron
2012-02-21 20:03 ` [PATCH 08/10] kvm: update to use very_unlikely() Jason Baron
2012-02-21 20:03 ` [PATCH 09/10] net: " Jason Baron
2012-02-21 20:03 ` [PATCH 10/10] jump label: Add docs better explaining the whole jump label mechanism Jason Baron
2012-02-29 10:15 ` [tip:perf/core] static keys: Add docs better explaining the whole 'struct static_key' mechanism tip-bot for Jason Baron
2012-02-21 20:09 ` [PATCH 00/10] jump label: introduce very_[un]likely + cleanups + docs H. Peter Anvin
2012-02-21 20:20 ` Jason Baron
2012-02-21 20:39 ` Steven Rostedt
2012-02-21 21:10 ` H. Peter Anvin
2012-02-21 21:16 ` Mathieu Desnoyers
2012-02-21 21:11 ` Mathieu Desnoyers
2012-02-22 7:32 ` Ingo Molnar
2012-02-22 7:53 ` Ingo Molnar
2012-02-22 8:01 ` H. Peter Anvin
2012-02-22 8:18 ` Ingo Molnar
2012-02-22 8:58 ` [PATCH] static keys: Introduce 'struct static_key', very_[un]likely(), static_key_slow_[inc|dec]() Ingo Molnar
2012-02-29 10:16 ` [tip:perf/core] static keys: Introduce 'struct static_key', static_key_true()/false() and static_key_slow_[inc|dec]() tip-bot for Ingo Molnar
2012-02-22 9:03 ` [PATCH] jump labels: Explain the .config option better Ingo Molnar
2012-02-22 15:08 ` [PATCH 00/10] jump label: introduce very_[un]likely + cleanups + docs H. Peter Anvin
2012-02-22 15:51 ` Ingo Molnar
2012-02-22 21:33 ` Paul Mackerras
2012-02-23 10:02 ` Ingo Molnar
2012-02-23 16:21 ` Jason Baron
2012-02-23 17:10 ` H. Peter Anvin
2012-02-24 9:11 ` Ingo Molnar
2012-02-23 17:18 ` Linus Torvalds
2012-02-23 22:33 ` Ingo Molnar
2012-02-23 22:39 ` Ingo Molnar
2012-02-23 22:44 ` Steven Rostedt
2012-02-23 23:18 ` Mathieu Desnoyers
2012-02-24 2:25 ` Jason Baron
2012-02-24 9:08 ` Ingo Molnar
2012-02-24 15:35 ` Jason Baron
2012-02-27 7:40 ` Ingo Molnar
2012-02-24 15:51 ` Mathieu Desnoyers
2012-02-24 16:06 ` Steven Rostedt
2012-02-24 7:52 ` static keys: Introduce 'struct static_key', static_key_true()/false() and static_key_slow_[inc|dec]() Ingo Molnar
2012-02-24 7:59 ` [PATCH] " Ingo Molnar
2012-02-24 7:54 ` [PATCH] static keys: Add docs better explaining the whole 'struct static_key' mechanism Ingo Molnar
2012-02-23 22:45 ` [PATCH 00/10] jump label: introduce very_[un]likely + cleanups + docs Linus Torvalds
2012-02-24 8:04 ` Ingo Molnar
2012-02-24 2:42 ` Jason Baron
2012-02-21 20:21 ` Steven Rostedt
2012-02-21 21:11 ` H. Peter Anvin
2012-02-22 6:50 ` Ingo Molnar
2012-02-22 7:03 ` H. Peter Anvin
2012-02-22 7:25 ` Ingo Molnar
2012-02-22 7:35 ` H. Peter Anvin
2012-02-22 7:48 ` Ingo Molnar
2012-02-22 7:55 ` H. Peter Anvin
2012-02-22 8:06 ` Ingo Molnar
2012-02-22 13:22 ` Steven Rostedt
2012-02-22 13:34 ` Ingo Molnar
2012-02-22 13:54 ` Steven Rostedt
2012-02-22 14:20 ` Mathieu Desnoyers
2012-02-22 14:36 ` Steven Rostedt
2012-02-22 14:56 ` Ingo Molnar
2012-02-22 15:11 ` H. Peter Anvin
2012-02-22 15:11 ` Peter Zijlstra
2012-02-22 15:47 ` Ingo Molnar
2012-02-22 15:12 ` Steven Rostedt
2012-02-22 15:15 ` H. Peter Anvin
2012-02-22 15:19 ` H. Peter Anvin
2012-02-22 15:42 ` Jason Baron
2012-02-22 15:54 ` Steven Rostedt
2012-02-22 15:56 ` Jason Baron
2012-02-22 16:08 ` Steven Rostedt
2012-02-22 15:19 ` Jason Baron
2012-02-22 15:40 ` H. Peter Anvin
2012-02-22 15:13 ` Peter Zijlstra
2012-02-22 15:32 ` Peter Zijlstra [this message]
2012-02-22 17:14 ` Richard Henderson
2012-02-22 18:28 ` H. Peter Anvin
2012-02-22 18:58 ` Jason Baron
2012-02-22 19:10 ` H. Peter Anvin
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