Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757301AbYGKMZX (ORCPT ); Fri, 11 Jul 2008 08:25:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754481AbYGKMZK (ORCPT ); Fri, 11 Jul 2008 08:25:10 -0400 Received: from nebensachen.de ([195.34.83.29]:49891 "EHLO mail.nebensachen.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752419AbYGKMZJ convert rfc822-to-8bit (ORCPT ); Fri, 11 Jul 2008 08:25:09 -0400 X-Hashcash: 1:20:080711:mingo@elte.hu::LBcRbinOUzAb8Yd5:00000Uzr X-Hashcash: 1:20:080711:roland@redhat.com::FrT/OANnqcYOFPQg:0000000000000000000000000000000000000000000039gB X-Hashcash: 1:20:080711:tglx@linutronix.de::qt6XLlEm23dhtLlb:000000000000000000000000000000000000000000023z/ X-Hashcash: 1:20:080711:akpm@linux-foundation.org::qEXnBXR4Xk402x53:0000000000000000000000000000000000001F2x X-Hashcash: 1:20:080711:torvalds@linux-foundation.org::CKbTwB8nhocCx+dd:000000000000000000000000000000006ojB X-Hashcash: 1:20:080711:linux-kernel@vger.kernel.org::2i8Mqjclewm1pHya:00000000000000000000000000000000026F4 X-Hashcash: 1:20:080711:edwintorok@gmail.com::ChDdrrGkP+KkHKoh:000000000000000000000000000000000000000004Ygb X-Hashcash: 1:20:080711:arjan@infradead.org::Ep1ULpSBAudIf3fA:0000000000000000000000000000000000000000008r5b From: Elias Oltmanns To: Ingo Molnar Cc: Roland McGrath , Thomas Gleixner , Andrew Morton , Linus Torvalds , linux-kernel@vger.kernel.org, =?iso-8859-1?Q?T=F6r=F6k?= Edwin , Arjan van de Ven Subject: Re: [PATCH] x86_64: fix delayed signals References: <20080710215039.2A143154218@magilla.localdomain> <20080711054605.GA17851@elte.hu> Date: Fri, 11 Jul 2008 14:24:31 +0200 In-Reply-To: <20080711054605.GA17851@elte.hu> (Ingo Molnar's message of "Fri, 11 Jul 2008 07:46:05 +0200") Message-ID: <87lk088v7k.fsf@denkblock.local> User-Agent: Gnus/5.110007 (No Gnus v0.7) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2032 Lines: 46 Ingo Molnar wrote: > * Roland McGrath wrote: > >> On three of the several paths in entry_64.S that call >> do_notify_resume() on the way back to user mode, we fail to properly >> check again for newly-arrived work that requires another call to >> do_notify_resume() before going to user mode. These paths set the >> mask to check only _TIF_NEED_RESCHED, but this is wrong. The other >> paths that lead to do_notify_resume() do this correctly already, and >> entry_32.S does it correctly in all cases. > > nice find! Roland, is this related to the thread started by Elias > Oltmanns yesterday: > > http://lkml.org/lkml/2008/7/10/57 > > which is also related to the thread started by Edwin T?r?k: > > http://lkml.org/lkml/2008/6/28/50 > > ? The weight of complains seems to be on the 64-bit side, in those > threads 32-bit systems seem to be implicated as well by latencytop. > Perhaps the 64-bit delays are related to the bug you fix and we could > chalk up the 32-bit delays to IO delays? Since I'm using a 32-bit machine, this patch isn't going to solve my particular problem. Still, I'm glad to hear that someone is looking at the assembly bits related to signal handling right now because that's precisely the part where I gave up to figure out for myself how signal handling works in the kernel. As for delayed signal handling on 32-bit platforms due to heavy disk I/O, I'm still reluctant to accept that signals should be delayed that much even though everything else that is not related to disk I/O works perfectly well. Now that I've seen some documentation for ftrace, I'll give it a go and try produce some helpful data. However, I'm rather busy right now and may not be able to do so before next week. Regards, Elias -- 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/