Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751590AbaFELdp (ORCPT ); Thu, 5 Jun 2014 07:33:45 -0400 Received: from mail-oa0-f44.google.com ([209.85.219.44]:42379 "EHLO mail-oa0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750723AbaFELdo (ORCPT ); Thu, 5 Jun 2014 07:33:44 -0400 Date: Thu, 05 Jun 2014 06:33:40 -0500 From: Felipe Contreras To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Andrew Morton , Linus Torvalds , Mel Gorman , KAMEZAWA Hiroyuki , Rik van Riel Message-ID: <53905594d284f_71f12992fc6a@nysa.notmuch> Subject: Interactivity regression since v3.11 in mm/vmscan.c Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, For a while I've noticed that my machine bogs down in certain situations, usually while doing heavy I/O operations, it is not just the I/O operations, but everything, including the graphical interface, even the mouse pointer. As far as I can recall this did not happen in the past. I noticed this specially on certain operations, for example updating a a game on Steam (to an exteranl USB 3.0 device), or copying TV episodes to a USB memory stick (probably flash-based). Today I decided to finally hunt down the problem, so I created a synthetic test that basically consists on copying a bunch of files from one drive to another (from an SSD to an external USB 3.0). This is pretty similar to what I noticed; the graphical interface slows down. Then I bisected the issue and it turns out that indeed it wasn't happening in the past, it started happening in v3.11, and it was triggered by this commit: e2be15f (mm: vmscan: stall page reclaim and writeback pages based on dirty/writepage pages encountered) Then I went back to the latest stable version (v3.14.5), and commented out the line I think is causing the slow down: if (nr_unqueued_dirty == nr_taken || nr_immediate) congestion_wait(BLK_RW_ASYNC, HZ/10); After that I don't notice the slow down any more. Anybody has any ideas how to fix the issue properly? -- Felipe Contreras -- 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/