Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932086AbcDLAYf (ORCPT ); Mon, 11 Apr 2016 20:24:35 -0400 Received: from mail-qg0-f43.google.com ([209.85.192.43]:34455 "EHLO mail-qg0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752686AbcDLAYc (ORCPT ); Mon, 11 Apr 2016 20:24:32 -0400 Date: Mon, 11 Apr 2016 20:24:28 -0400 From: Tejun Heo To: Jakob Unterwurzacher Cc: Miklos Szeredi , fuse-devel , Linux-Fsdevel , Kernel Mailing List Subject: Re: [fuse-devel] Horrible mmap write performance (kernel writeback issue?) Message-ID: <20160412002428.GQ24661@htj.duckdns.org> References: <56E7C009.3070008@gmail.com> <56F70255.6070806@gmail.com> <20160330184732.GO7822@mtj.duckdns.org> <570B5A9A.6070104@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <570B5A9A.6070104@gmail.com> 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: 432 Lines: 14 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. Thanks. -- tejun