Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932301AbVJaPxc (ORCPT ); Mon, 31 Oct 2005 10:53:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932289AbVJaPxc (ORCPT ); Mon, 31 Oct 2005 10:53:32 -0500 Received: from smtp.osdl.org ([65.172.181.4]:61130 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S932282AbVJaPxb (ORCPT ); Mon, 31 Oct 2005 10:53:31 -0500 Date: Mon, 31 Oct 2005 07:53:20 -0800 (PST) From: Linus Torvalds To: Jens Axboe cc: Tejun Heo , Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org Subject: Re: [PATCH][noop-iosched] don't reuse a freed request In-Reply-To: <20051031082354.GO19267@suse.de> Message-ID: References: <20051031023024.GC5632@mandriva.com> <20051031074022.GN19267@suse.de> <4365D01D.2040406@gmail.com> <20051031082354.GO19267@suse.de> 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: 2708 Lines: 67 On Mon, 31 Oct 2005, Jens Axboe wrote: > > So either we disable merging for noop by setting REQ_NOMERGE in > elevator_noop_add_request(), or we add a noop_list and do the > dispatching like in the other io schedulers. I'd prefer the latter, > merging is still beneficial for noop (and it has always done it). > > For now, we should add the former. > > Signed-off-by: Jens Axboe Btw, Jens, I appreciate seeing the discussion history when applying a patch, but at the same time I do _not_ want to use it as a commit message, it's just too confusing and worthless in that context. And yet, your final comments don't much make sense without the background, so I can't just use them either. So, I rewrote the explanation. Which is fine, but I wish people who sent patches would think more about what message they want to have in the commit logs, so that (a) Lazy-Linus doesn't have to write his own message and (b) so that the message is correct when Lazy-and-Stupid-Linus sometimes doesn't necessarily see/understand all the problems it fixes. Btw, the email-patch-sending protocol still allows for putting all the ugly history in for my (and the mailing lists) pleasure: that's what the "---" marker after the explanation is for. So you can _both_ have a nice clean commit message _and_ give more of a historical background for the patch. Anyway, in this case, the commit message ended up looking like this:: commit 581c1b14394aee60aff46ea67d05483261ed6527 Author: Jens Axboe Date: Mon Oct 31 09:23:54 2005 +0100 [PATCH] noop-iosched: avoid corrupted request merging Tejun Heo notes: "I'm currently debugging this. The problem is that we are using the generic dispatch queue directly in the noop sched and merging is NOT allowed on dispatch queues but generic handling of last_merge tries to merge requests. I'm still trying to verify this, so I'll be back with results soon." In the meantime, disable merging for noop by setting REQ_NOMERGE in elevator_noop_add_request(). Eventually, we should add a noop_list and do the dispatching like in the other io schedulers. Merging is still beneficial for noop (and it has always done it). Signed-off-by: Jens Axboe Signed-off-by: Linus Torvalds which is basically your email cleaned up and compressed into a readable commit message. 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/