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Subject: Re: [PATCH] syscall latency improvement #1
To: torvalds@transmeta.com (Linus Torvalds)
Date: Sat, 26 Jan 2002 18:39:35 +0000 (GMT)
Cc: dhowells@redhat.com (David Howells), linux-kernel@vger.kernel.org
In-Reply-To: <Pine.LNX.4.33.0201251626490.2042-100000@penguin.transmeta.com> from "Linus Torvalds" at Jan 25, 2002 04:39:18 PM
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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
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> NOTE! There are potentially other ways to do all of this, _without_ losing
> atomicity. For example, you can move the "flags" value into the slot saved
> for the CS segment (which, modulo vm86, will always be at a constant
> offset on the stack), and make CS=0 be the work flag. That will cause the
> CPU to trap atomically at the "iret".

Is the test even needed. Suppose we instead patch the return stack if we
set need_resched/sigpending, and do it on the rare occassion we set the
value.
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