From: Keith Mannthey Subject: Barriers per second while doing Odirect Random Writes Date: Mon, 26 Apr 2010 00:06:17 -0700 Message-ID: <1272265577.9664.57.camel@keith-laptop> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit To: "linux-ext4@vger.kernel.org" Return-path: Received: from e9.ny.us.ibm.com ([32.97.182.139]:36226 "EHLO e9.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753717Ab0DZHGT (ORCPT ); Mon, 26 Apr 2010 03:06:19 -0400 Received: from d01relay01.pok.ibm.com (d01relay01.pok.ibm.com [9.56.227.233]) by e9.ny.us.ibm.com (8.14.3/8.13.1) with ESMTP id o3Q6rnc6015216 for ; Mon, 26 Apr 2010 02:53:49 -0400 Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by d01relay01.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o3Q76I81133276 for ; Mon, 26 Apr 2010 03:06:18 -0400 Received: from d01av04.pok.ibm.com (loopback [127.0.0.1]) by d01av04.pok.ibm.com (8.14.3/8.13.1/NCO v10.0 AVout) with ESMTP id o3Q76IYF030640 for ; Mon, 26 Apr 2010 03:06:18 -0400 Received: from [9.65.186.211] (sig-9-65-186-211.mts.ibm.com [9.65.186.211]) by d01av04.pok.ibm.com (8.14.3/8.13.1/NCO v10.0 AVin) with ESMTP id o3Q76HYH030595 for ; Mon, 26 Apr 2010 03:06:17 -0400 Sender: linux-ext4-owner@vger.kernel.org List-ID: Ted and all, While using this FFSB test profile: http://btrfs.boxacle.net/repository/raid/2010-04-14_2004//ext4-2.6.34-rc3-nobarrier//btrfs1.ffsb.random_writes_odirect__threads_0128.10-04-21_17.38.39/benchmark/profile (The profile is 128 threads of all odirect random writes. ) on my raid box I am seeing (via Darricks block_barrier tracepoint) right about 32 barriers per second. Initial analysis using perf shows kdmflush as the cause. I will continue to look into this. Thanks, Keith Mannthey LTC FS-Dev