From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from plane.gmane.org ([80.91.229.3]:35808 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751691Ab3KZAu2 (ORCPT ); Mon, 25 Nov 2013 19:50:28 -0500 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1Vl6rC-0005Ux-Ua for linux-btrfs@vger.kernel.org; Tue, 26 Nov 2013 01:50:26 +0100 Received: from p5b00795b.dip0.t-ipconnect.de ([91.0.121.91]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 26 Nov 2013 01:50:26 +0100 Received: from holger.hoffstaette by p5b00795b.dip0.t-ipconnect.de with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 26 Nov 2013 01:50:26 +0100 To: linux-btrfs@vger.kernel.org From: "Holger Hoffstaette" Subject: Re: btrfs scrub ioprio Date: Tue, 26 Nov 2013 01:50:15 +0100 Message-ID: References: <5292C7F7.8010200@jrs-s.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Sun, 24 Nov 2013 22:45:59 -0500, Jim Salter wrote: > TL;DR scrub's ioprio argument isn't really helpful - a scrub murders > system performance til it's done. > > My system: > > 3.11 kernel (from Ubuntu Saucy) I don't run Ubuntu, but *maybe* they use the deadline IO scheduler by default, which does not handle IO priorities (by design). So maybe make sure your devices don't say "deadline" in /sys/block/sdX/queue/scheduler, and if they do, set them to cfq. -h