From: William Lee Irwin III <wli@holomorphy.com>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Albert Cahalan <albert@users.sf.net>,
Jakub Jelinek <jakub@redhat.com>,
Albert Cahalan <albert@users.sourceforge.net>,
linux-kernel mailing list <linux-kernel@vger.kernel.org>,
ak@muc.de
Subject: Re: get_current is __pure__, maybe __const__ even
Date: Wed, 15 Sep 2004 20:23:01 -0700 [thread overview]
Message-ID: <20040916032301.GJ9106@holomorphy.com> (raw)
In-Reply-To: <4148FED6.100@yahoo.com.au>
On Wed, Sep 15, 2004 at 10:10:20PM -0400, Albert Cahalan wrote:
>>> I don't think even barrier() is needed. Suppose gcc were to cache
>>> the value of current over a schedule. Who cares? It'll be the same
>>> after schedule() as it was before.
William Lee Irwin III wrote:
>> Not over a call to schedule(). In the midst of schedule().
On Thu, Sep 16, 2004 at 12:47:50PM +1000, Nick Piggin wrote:
> In a way, it is. Because after context_switch, the stack
> and registers have been replaced by the new task. So if
> current was cached somewhere before that task had scheduled
> off, then it still would be correct now that it is scheduled
> back on.
> At points *within* context_switch, current won't be right,
> but AFAIKS current is never used in there.
We have a clobber in inline asm and a manual barrier() so we don't need
to change anything if current were to be properly CSE'd. It's somewhat
academic; if current were (mis)used there, it would change.
-- wli
next prev parent reply other threads:[~2004-09-16 3:23 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-15 22:50 get_current is __pure__, maybe __const__ even Albert Cahalan
2004-09-15 23:15 ` Jakub Jelinek
2004-09-15 23:29 ` William Lee Irwin III
2004-09-16 2:10 ` Albert Cahalan
2004-09-16 2:36 ` William Lee Irwin III
2004-09-16 2:47 ` Nick Piggin
2004-09-16 3:23 ` William Lee Irwin III [this message]
2004-09-16 3:49 ` Albert Cahalan
2004-09-16 3:59 ` William Lee Irwin III
2004-09-16 9:04 ` Russell King
2004-09-16 9:11 ` Andi Kleen
2004-09-16 9:30 ` Russell King
2004-09-16 11:03 ` Andi Kleen
2004-09-16 14:36 ` Russell King
2004-09-15 23:27 ` William Lee Irwin III
[not found] <2ER4z-46B-17@gated-at.bofh.it>
2004-09-16 6:58 ` Andi Kleen
2004-09-16 13:43 ` Albert Cahalan
2004-09-16 14:14 ` Albert Cahalan
2004-09-16 19:27 ` Andi Kleen
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