Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932569AbXBNUf4 (ORCPT ); Wed, 14 Feb 2007 15:35:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932573AbXBNUf4 (ORCPT ); Wed, 14 Feb 2007 15:35:56 -0500 Received: from kanga.kvack.org ([66.96.29.28]:51376 "EHLO kanga.kvack.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932569AbXBNUfz (ORCPT ); Wed, 14 Feb 2007 15:35:55 -0500 Date: Wed, 14 Feb 2007 15:34:38 -0500 From: Benjamin LaHaise To: Davide Libenzi Cc: Russell King , Ingo Molnar , Linux Kernel Mailing List , Linus Torvalds , Arjan van de Ven , Christoph Hellwig , Andrew Morton , Alan Cox , Ulrich Drepper , Zach Brown , Evgeniy Polyakov , "David S. Miller" , Suparna Bhattacharya , Thomas Gleixner Subject: Re: [patch 06/11] syslets: core, documentation Message-ID: <20070214203438.GL32271@kvack.org> References: <20060529212109.GA2058@elte.hu> <20070213142042.GG638@elte.hu> <20070214103655.GB4241@flint.arm.linux.org.uk> <20070214105039.GC6801@elte.hu> <20070214110419.GC4241@flint.arm.linux.org.uk> <20070214180344.GI32271@kvack.org> <20070214200347.GK32271@kvack.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1186 Lines: 23 On Wed, Feb 14, 2007 at 12:14:29PM -0800, Davide Libenzi wrote: > I think you may have mis-interpreted my words. *When* a schedule would > block a synco execution try, then you do have a context switch. Noone > argue that, and the code is clear. The sys_async_exec thread will block, > and a newly woke up thread will re-emerge to sys_async_exec with a NULL > returned to userspace. But in a "cachehit" case (no schedule happens > during the syscall/*let execution), there is no context switch at all. > That is the whole point of the optimization. And I will repeat myself: that cannot be done. Tell me how the following what if scenario works: you're in an MMX optimized memory copy and you take a page fault. How does returning to the submittor of the async operation get the correct MMX state restored? It doesn't. -ben -- "Time is of no importance, Mr. President, only life is important." Don't Email: . - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/