Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752346AbXLJWGY (ORCPT ); Mon, 10 Dec 2007 17:06:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751773AbXLJWGR (ORCPT ); Mon, 10 Dec 2007 17:06:17 -0500 Received: from rv-out-0910.google.com ([209.85.198.189]:8982 "EHLO rv-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751762AbXLJWGQ (ORCPT ); Mon, 10 Dec 2007 17:06:16 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:sender:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references:x-google-sender-auth; b=qPR6v6cxBLhcj08EU+a9b4cTMvsFf5JZi7Z++WpZwLsaNYodKlJ3lQ/YkvqD9AaqaPOrhE5vbs3h8aJ/DokHT7zQ5+Oo5FxnIWQ7K06PT155TQw6RiIuu3a2m9dBFF13X5ZVfOT54cswykNIF16eboKUuWkBYXMy/yfAVfhjKa4= Message-ID: <84144f020712101406i562ca243vd7b5fe6bfd1db05b@mail.gmail.com> Date: Tue, 11 Dec 2007 00:06:15 +0200 From: "Pekka Enberg" To: "Jonathan Corbet" Subject: Re: [RFC] [PATCH] A clean approach to writeout throttling Cc: "Daniel Phillips" , "Andrew Morton" , "Peter Zijlstra" , linux-kernel@vger.kernel.org In-Reply-To: <25797.1197322312@lwn.net> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <200712051603.02183.phillips@phunq.net> <25797.1197322312@lwn.net> X-Google-Sender-Auth: de09007a045c7e43 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1037 Lines: 25 Hi, On Dec 10, 2007 11:31 PM, Jonathan Corbet wrote: > I'm just getting around to looking at this. One thing jumped out at me: > > > + if (bio->bi_throttle) { > > + struct request_queue *q = bio->bi_queue; > > + bio->bi_throttle = 0; /* or detect multiple endio and err? */ > > + atomic_add(bio->bi_throttle, &q->available); > > + wake_up(&q->throttle_wait); > > + } > > I'm feeling like I must be really dumb, but...how can that possibly > work? You're zeroing >bi_throttle before adding it back into > q->available, so the latter will never increase... Heh, well, that's ok as long as bio->bi_vcnt is set to zero and I think we have some md raid drivers do just that... ;-) Pekka -- 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/