Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751672Ab3HTIHw (ORCPT ); Tue, 20 Aug 2013 04:07:52 -0400 Received: from mail-ph.de-nserver.de ([85.158.179.214]:56241 "EHLO mail-ph.de-nserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751181Ab3HTIHu (ORCPT ); Tue, 20 Aug 2013 04:07:50 -0400 X-Fcrdns: No Message-ID: <521323D1.1070503@profihost.ag> Date: Tue, 20 Aug 2013 10:07:45 +0200 From: Stefan Priebe - Profihost AG User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130804 Thunderbird/17.0.8 MIME-Version: 1.0 To: Kent Overstreet CC: Jens Axboe , linux-kernel@vger.kernel.org, linux-bcache@vger.kernel.org Subject: Re: bcache: Fix a writeback performance regression References: <20130814225904.GA6427@kmo-pixel> <520C788A.1060208@profihost.ag> <520DFAB4.1050402@profihost.ag> <52114614.4070509@profihost.ag> <20130819222718.GA32104@kmo-pixel> <52132243.8050803@profihost.ag> In-Reply-To: <52132243.8050803@profihost.ag> X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-User-Auth: Auth by hostmaster@profihost.com through 85.158.179.66 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1262 Lines: 29 Am 20.08.2013 10:01, schrieb Stefan Priebe - Profihost AG: > Am 20.08.2013 00:27, schrieb Kent Overstreet: >> On Mon, Aug 19, 2013 at 12:09:24AM +0200, Stefan Priebe wrote: >>> >>> Vanilla 3.10.7 + bcache: Fix a writeback performance regression >>> >>> http://pastebin.com/raw.php?i=LXZk4cMH >> >> Whoops, at first I thought this was the same bug as one I'd already been >> chasing down that had been a harmless bug - turns out I didn't look >> closely enough at the backtrace. >> >> What happened is background writeback is deadlocking, because for some >> reason the workqueue it's running out of is a singlethreaded workqueue, >> so as soon as it decides to queue enough writeback bios that it has to >> sleep on that semaphore (which often won't happen due to the PD >> controller based ratelimiting) - boom, deadlock. >> >> Here's the fixup patch I just tested and am applying: Oh i'm now seeing very high CPU spikes of kworker... i don't see if i remove bcache: Fix a writeback performance regression. Stefan -- 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/