From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760588AbYCHBx2 (ORCPT ); Fri, 7 Mar 2008 20:53:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753453AbYCHBxM (ORCPT ); Fri, 7 Mar 2008 20:53:12 -0500 Received: from po-out-1718.google.com ([72.14.252.156]:4716 "EHLO po-out-1718.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759333AbYCHBxK (ORCPT ); Fri, 7 Mar 2008 20:53:10 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=dM8LIFGMsPNB5D5CgW5CXrahzQG/tKEMJnK/Cga+K88ifk8JsLPRaCNRVJfqBmB0rFduukeVKtSpGTngXlvnH9SR4CCbsZwFPdrsMz2z0cUI3pmMkmomFMcxmSSVsA/BO2bBMFuwOo7ixN3koVBGx8/BdmDWaKMs4dGkxcrox3M= Message-ID: <4a3acf9f0803071753x19043628t2ffda8ce6e946e18@mail.gmail.com> Date: Sat, 8 Mar 2008 09:53:07 +0800 From: "=?GB2312?B?xNq6y9e319k=?=" To: linux-kernel Subject: Question about pdflush's two ratio? MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, buddy, In these days, I'm watching about how the pdflush kernel thread implemented. But we I saw there are two "*_ratio", I was puzzled about these. My kernel version is 2.6.9 and I found get_dirty_limits() in page-writeback.c in KERNEL_SOURCE/mm. After read the source and annotation about the function , I got that idea about 1. *dirty_ratio* is just for work with the number in system page cache. It means if the (dirty pages number in system)/(total number pages) is above the ratio , then we start pdflush. 2. *background_ratio* is just for every process. It means if there were a single_process write pages and (its dirty pages) / (total number pages in system) is above th ratio, then we also start pdflush. This is my interpetation. But does it correct? Thx. Jiancong