From: Ingo Molnar <mingo@elte.hu>
To: Linus Torvalds <torvalds@osdl.org>
Cc: Andrew Morton <akpm@osdl.org>,
Chuck Ebbert <76306.1226@compuserve.com>,
In Cognito <defend.the.world@gmail.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Andi Kleen <ak@suse.de>
Subject: Re: Sysenter crash with Nested Task Bit set
Date: Mon, 18 Sep 2006 17:06:50 +0200 [thread overview]
Message-ID: <20060918150650.GA10336@elte.hu> (raw)
In-Reply-To: <Pine.LNX.4.64.0609180741520.4388@g5.osdl.org>
* Linus Torvalds <torvalds@osdl.org> wrote:
> And sysenter really is very special because of the weak trap
> semantics. Damn. We could either fix it in the sysenter code-path, or
> in the task-switch one, and both of them are timing-critical, but task
> switching perhaps just a tad less so.
agreed. Context-switching is 10 times less frequent on most workloads
than syscalls, so if it takes 10 cycles in the context-switch path to
eliminate a 1 cycle overhead in the syscall-entry path then we are still
break-even on average. In this case the overhead is similar i think, so
the switch_to() fix is preferable.
Ingo
next prev parent reply other threads:[~2006-09-18 15:15 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-09-18 3:51 Sysenter crash with Nested Task Bit set Chuck Ebbert
2006-09-18 5:25 ` Andrew Morton
2006-09-18 8:44 ` Mike Galbraith
2006-09-18 15:11 ` Linus Torvalds
2006-09-18 15:06 ` Ingo Molnar [this message]
2006-09-18 15:29 ` Andi Kleen
2006-09-18 15:24 ` Ingo Molnar
2006-09-18 16:02 ` Linus Torvalds
2006-09-18 16:10 ` Linus Torvalds
2006-09-18 16:24 ` Jeremy Fitzhardinge
2006-09-18 16:12 ` Benjamin LaHaise
2006-09-18 16:39 ` Andi Kleen
2006-09-18 19:01 ` Jeremy Fitzhardinge
[not found] <5a20704e0609171603s55ca52bap71dc2fa2c05d6741@mail.gmail.com>
2006-09-17 23:08 ` In Cognito
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