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From: David Howells <dhowells@redhat.com>
To: David Howells <dhowells@redhat.com>
Cc: Roman Zippel <zippel@linux-m68k.org>,
	Christoph Hellwig <hch@infradead.org>,
	"Adam J. Richter" <adam@yggdrasil.com>,
	linux-kernel@vger.kernel.org
Subject: Re: Patch: linux-2.5.29 __downgrade_write() for CONFIG_RWSEM_GENERIC_SPINLOCK
Date: Mon, 29 Jul 2002 10:13:55 +0100	[thread overview]
Message-ID: <28550.1027934035@warthog.cambridge.redhat.com> (raw)
In-Reply-To: Message from David Howells <dhowells@redhat.com>  of "Mon, 29 Jul 2002 09:31:55 BST." <20869.1027931515@warthog.cambridge.redhat.com>


> Roman Zippel <zippel@linux-m68k.org> wrote:
> > Did you look at the code? gcc should be able to optimize that itself.
> 
> Maybe... gcc should also optimise my version to the same extent, I think
> (the result of one of the additional tests is known at compile time, and the
> other one is the same as the next test down). What I'm unsure about is how
> gcc will handle the variable being stored in memory not marked volatile and
> then retrieved again; whether it'll actually issue a read, or just assume
> it's got it cached.

It doesn't appear to make any difference which way it is done. The i386 code
from both looks the same.

David

  reply	other threads:[~2002-07-29  9:10 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-07-28 17:50 Patch: linux-2.5.29 __downgrade_write() for CONFIG_RWSEM_GENERIC_SPINLOCK Adam J. Richter
2002-07-28 18:07 ` Roman Zippel
2002-07-28 18:08 ` Christoph Hellwig
2002-07-28 22:55   ` Roman Zippel
2002-07-29  7:42     ` David Howells
2002-07-29  8:01       ` Roman Zippel
2002-07-29  8:31         ` David Howells
2002-07-29  9:13           ` David Howells [this message]
2002-07-29 11:42             ` Roman Zippel
2002-07-29 12:08               ` David Howells
2002-07-29 12:46                 ` Roman Zippel

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