Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 12 Feb 2003 12:17:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 12 Feb 2003 12:17:44 -0500 Received: from neon-gw-l3.transmeta.com ([63.209.4.196]:62215 "EHLO neon-gw.transmeta.com") by vger.kernel.org with ESMTP id ; Wed, 12 Feb 2003 12:17:43 -0500 To: linux-kernel@vger.kernel.org From: torvalds@transmeta.com (Linus Torvalds) Subject: Re: [Bug 350] New: i386 context switch very slow compared to 2.4 due to wrmsr (performance) Date: Wed, 12 Feb 2003 17:24:08 +0000 (UTC) Organization: Transmeta Corporation Message-ID: References: <629040000.1045013743@flay> <20030212041848.GA9273@bjl1.jlokier.co.uk> <20030212101831.GB10422@bjl1.jlokier.co.uk> X-Trace: palladium.transmeta.com 1045070837 25979 127.0.0.1 (12 Feb 2003 17:27:17 GMT) X-Complaints-To: news@transmeta.com NNTP-Posting-Date: 12 Feb 2003 17:27:17 GMT Cache-Post-Path: palladium.transmeta.com!unknown@penguin.transmeta.com X-Cache: nntpcache 2.4.0b5 (see http://www.nntpcache.org/) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 857 Lines: 24 In article <20030212101831.GB10422@bjl1.jlokier.co.uk>, Jamie Lokier wrote: > >I meant: the trampoline _stack_ lives in the TSS. > >There is no trampoline _code_. Ahh, ok. That sounds quite doable, and all my complaints go away. It still leaves the debug exception and NMI issue. The debug exception case is easy to trigger: use gdb to single-step through the user-lebel fast system call code, and you _will_ get a debug exception on the very first kernel instruction (which is also the one that doesn't have a valid stack). So anybody want to actually try to implement this? Linus - 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/