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From: "David S. Miller" <davem@davemloft.net>
To: torvalds@osdl.org
Cc: bunk@stusta.de, akpm@osdl.org, linux-kernel@vger.kernel.org
Subject: Re: [2.6 patch] offer CC_OPTIMIZE_FOR_SIZE only if EXPERIMENTAL
Date: Wed, 14 Dec 2005 22:45:44 -0800 (PST)	[thread overview]
Message-ID: <20051214.224544.56187291.davem@davemloft.net> (raw)
In-Reply-To: <Pine.LNX.4.64.0512141528140.3292@g5.osdl.org>

From: Linus Torvalds <torvalds@osdl.org>
Date: Wed, 14 Dec 2005 15:32:28 -0800 (PST)

> Of course, the really right thing would be to chase down what goes
> wrong with -Os.

It turns out to be a sparc64 bug, technically, in my case.

What happens is that with -Os gcc _INLINES_ schedule() into
wait_for_completion().  No that's not a typo, when optimizing
for space it inlines a huge function like schedule() whereas
without -Os it does not. :-/

Anyways, switch_to() in sparc64 (and sparc) does not work properly
when this happens.  schedule() needs to execute in it's own stack
frame for the stack switching in switch_to() to work.

Would anyone be against adding "noinline" to kernel/sched.c:schedule()?
I'm about to test that, but I'm extremely positive that it makes the
problem go away.

  parent reply	other threads:[~2005-12-15  6:54 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-12-14 19:10 [2.6 patch] fix the EMBEDDED menu Adrian Bunk
2005-12-14 22:05 ` Andrew Morton
2005-12-14 22:13   ` [2.6 patch] offer CC_OPTIMIZE_FOR_SIZE only if EXPERIMENTAL Adrian Bunk
2005-12-14 22:18     ` Jesper Juhl
2005-12-14 22:28       ` Jesper Juhl
2005-12-15  0:40         ` Dave Jones
2005-12-15  5:24           ` David S. Miller
2005-12-15 15:01           ` Krzysztof Halasa
2005-12-15 17:35             ` Dave Jones
     [not found]             ` <7c3341450601191017o796faf45r2cc5c8e544dcfe11@mail.gmail.com>
2006-01-19 19:13               ` Dave Jones
2005-12-15 19:20         ` Denis Vlasenko
2005-12-14 22:22     ` Andrew Morton
2005-12-14 22:26       ` Adrian Bunk
2005-12-14 22:30       ` Russell King
2005-12-14 22:36     ` Linus Torvalds
2005-12-14 22:44       ` Adrian Bunk
2005-12-14 22:46         ` Adrian Bunk
2005-12-14 23:32         ` Linus Torvalds
2005-12-14 23:43           ` Adrian Bunk
2005-12-15  6:45           ` David S. Miller [this message]
2005-12-14 23:48       ` David S. Miller
2006-01-19 17:59       ` Eric Lammerts
2005-12-14 22:17   ` [2.6 patch] fix the EMBEDDED menu Russell King
2005-12-14 22:24     ` Adrian Bunk
2005-12-17 21:20     ` Nicolas Pitre
2005-12-15 13:01   ` Rogério Brito

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