Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753417Ab3HUXrj (ORCPT ); Wed, 21 Aug 2013 19:47:39 -0400 Received: from mail-pa0-f42.google.com ([209.85.220.42]:65088 "EHLO mail-pa0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753373Ab3HUXrh (ORCPT ); Wed, 21 Aug 2013 19:47:37 -0400 Date: Wed, 21 Aug 2013 16:47:15 -0700 From: Kent Overstreet To: Stefan Priebe - Profihost AG Cc: Jens Axboe , linux-kernel@vger.kernel.org, linux-bcache@vger.kernel.org Subject: Re: bcache: Fix a writeback performance regression Message-ID: <20130821234715.GA4630@moria.home.lan> 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> <521323D1.1070503@profihost.ag> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <521323D1.1070503@profihost.ag> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1449 Lines: 30 On Tue, Aug 20, 2013 at 10:07:45AM +0200, Stefan Priebe - Profihost AG wrote: > 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. Are you able to reproduce it? I'm not having any luck reproducing it... -- 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/