Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932338AbcDLLJJ (ORCPT ); Tue, 12 Apr 2016 07:09:09 -0400 Received: from mail-qk0-f179.google.com ([209.85.220.179]:35685 "EHLO mail-qk0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932649AbcDLLJG (ORCPT ); Tue, 12 Apr 2016 07:09:06 -0400 Date: Tue, 12 Apr 2016 07:09:03 -0400 From: Tejun Heo To: Ashish Sangwan Cc: Jakob Unterwurzacher , Miklos Szeredi , fuse-devel , Linux-Fsdevel , Kernel Mailing List Subject: Re: [fuse-devel] Horrible mmap write performance (kernel writeback issue?) Message-ID: <20160412110903.GR24661@htj.duckdns.org> References: <56E7C009.3070008@gmail.com> <56F70255.6070806@gmail.com> <20160330184732.GO7822@mtj.duckdns.org> <570B5A9A.6070104@gmail.com> <20160412002428.GQ24661@htj.duckdns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 827 Lines: 26 Hello, On Tue, Apr 12, 2016 at 02:54:08PM +0530, Ashish Sangwan wrote: > On Tue, Apr 12, 2016 at 5:54 AM, Tejun Heo wrote: > > Hello, > > > > On Mon, Apr 11, 2016 at 10:04:42AM +0200, Jakob Unterwurzacher wrote: > >> What seems to be happening in the kernel is that the estimated device bandwith > >> drops to zero. I'm not even sure how this works for FUSE, but that's what I > >> gathered from some printk debugging. > > > > Yeah, writeback bw getting messed up is the most likely cause. Prolly > > some silly bug. I can reproduce the problem. Looking into it. > > Probably you want to look into: > https://lkml.org/lkml/2016/3/10/21 > > The patch mentioned above solves the issue for me. Heh, I tracked it down to wb_over_bg_thresh() and fell asleep. Yeah, that is the right fix. Thanks. -- tejun