Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932527AbXBNUD6 (ORCPT ); Wed, 14 Feb 2007 15:03:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932529AbXBNUD6 (ORCPT ); Wed, 14 Feb 2007 15:03:58 -0500 Received: from kanga.kvack.org ([66.96.29.28]:50999 "EHLO kanga.kvack.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932528AbXBNUD5 (ORCPT ); Wed, 14 Feb 2007 15:03:57 -0500 Date: Wed, 14 Feb 2007 15:03:47 -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: <20070214200347.GK32271@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> 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: 1107 Lines: 22 On Wed, Feb 14, 2007 at 11:45:23AM -0800, Davide Libenzi wrote: > Sort of, except that the whole thing can complete syncronously w/out > context switches. The real point of the whole fibrils/syslets solution is > that kind of optimization. The solution is as good as it is now, for Except that You Can't Do That (tm). Try to predict beforehand if the code path being followed will touch the FPU or SSE state, and you can't. There is no way to avoid the context switch overhead, as you have to preserve things so that whatever state is being returned to the user is as it was. Unless you plan on resetting the state beforehand, but then you have to call into arch specific code that ends up with a comparable overhead to the context switch. -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/