Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030334AbXBZRUU (ORCPT ); Mon, 26 Feb 2007 12:20:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030346AbXBZRUU (ORCPT ); Mon, 26 Feb 2007 12:20:20 -0500 Received: from smtp.osdl.org ([65.172.181.24]:54135 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030334AbXBZRUS (ORCPT ); Mon, 26 Feb 2007 12:20:18 -0500 Date: Mon, 26 Feb 2007 09:10:22 -0800 (PST) From: Linus Torvalds To: Benjamin LaHaise cc: Jiri Slaby , Uwe Bugla , akpm@linux-foundation.org, bunk@stusta.de, linux-kernel@vger.kernel.org, Stephane Eranian , Andi Kleen Subject: Re: bug in kernel 2.6.21-rc1-git1: conventional floppy drive cannot be mounted without hanging up the whole system In-Reply-To: <20070226163429.GL26583@kvack.org> Message-ID: References: <20070224175424.176030@gmx.net> <45E2B88B.1090706@gmail.com> <45E2F8C5.3080905@gmail.com> <20070226163429.GL26583@kvack.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1700 Lines: 37 On Mon, 26 Feb 2007, Benjamin LaHaise wrote: > > Side note: this patch adds several function calls (4), several additional > L1 cache touches and a generally inefficient code path to *every single > interrupt that exits from the idle poll*, not to mention the extra (useless, > as it doesn't get used on 99.9% of deployed systems) function call and cache > touches to every single interrupt. It is in fact possible that the floppy failure might just be from some timing-dependent thing, and the slowdown itself is the problem. Although I do find that a bit unlikely, since machines these days are about a million times faster than they used to be, so even if it's unnecessarily slow, it shouldn't be noticeable for a floppy drive. > Keep in mind that systems acting as routers will often be sitting in > the idle loop when processing interrupts. At the very least this > overhead (which is noticable on profiles) should be configurable. I > don't think that my 586 class embedded routers really need this crap to > be going into the kernel. I'm inclined to agree. Considering that the patch is known to cause problems, and that it's apparently broken on x86 *anyway* (the idle_notifier_register function isn't even exported), and considering that it's clearly bad for interrupt performance and could have been done a lot better, I would suggest just ripping it all out. And I think we should do the same for x86-64 too.. 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/