From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757270Ab0IUVov (ORCPT ); Tue, 21 Sep 2010 17:44:51 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:44627 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752475Ab0IUVou (ORCPT ); Tue, 21 Sep 2010 17:44:50 -0400 Date: Tue, 21 Sep 2010 14:44:13 -0700 From: Andrew Morton To: Mel Gorman Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Linux Kernel List , Johannes Weiner , Minchan Kim , Wu Fengguang , KAMEZAWA Hiroyuki , KOSAKI Motohiro Subject: Re: [PATCH 8/8] writeback: Do not sleep on the congestion queue if there are no congested BDIs or if significant congestion is not being encountered in the current zone Message-Id: <20100921144413.abc45d2f.akpm@linux-foundation.org> In-Reply-To: <20100920095239.GE1998@csn.ul.ie> References: <1284553671-31574-1-git-send-email-mel@csn.ul.ie> <1284553671-31574-9-git-send-email-mel@csn.ul.ie> <20100916152810.cb074e9f.akpm@linux-foundation.org> <20100920095239.GE1998@csn.ul.ie> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.9; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 20 Sep 2010 10:52:39 +0100 Mel Gorman wrote: > > > This patch tracks how many pages backed by a congested BDI were found during > > > scanning. If all the dirty pages encountered on a list isolated from the > > > LRU belong to a congested BDI, the zone is marked congested until the zone > > > reaches the high watermark. > > > > High watermark, or low watermark? > > > > High watermark. The check is made by kswapd. > > > The terms are rather ambiguous so let's avoid them. Maybe "full" > > watermark and "empty"? > > > > Unfortunately they are ambiguous to me. I know what the high watermark > is but not what the full or empty watermarks are. Really. So what's the "high" watermark? From the above text I'm thinking that you mean the high watermark is when the queue has a small number of requests and the low watermark is when the queue has a large number of requests. I'd have thought that this is backwards: the "high" watermark is when the queue has a large (ie: high) number of requests. A problem. How do we fix it? From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH 8/8] writeback: Do not sleep on the congestion queue if there are no congested BDIs or if significant congestion is not being encountered in the current zone Date: Tue, 21 Sep 2010 14:44:13 -0700 Message-ID: <20100921144413.abc45d2f.akpm@linux-foundation.org> References: <1284553671-31574-1-git-send-email-mel@csn.ul.ie> <1284553671-31574-9-git-send-email-mel@csn.ul.ie> <20100916152810.cb074e9f.akpm@linux-foundation.org> <20100920095239.GE1998@csn.ul.ie> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Linux Kernel List , Johannes Weiner , Minchan Kim , Wu Fengguang , KAMEZAWA Hiroyuki , KOSAKI Motohiro To: Mel Gorman Return-path: In-Reply-To: <20100920095239.GE1998@csn.ul.ie> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Mon, 20 Sep 2010 10:52:39 +0100 Mel Gorman wrote: > > > This patch tracks how many pages backed by a congested BDI were found during > > > scanning. If all the dirty pages encountered on a list isolated from the > > > LRU belong to a congested BDI, the zone is marked congested until the zone > > > reaches the high watermark. > > > > High watermark, or low watermark? > > > > High watermark. The check is made by kswapd. > > > The terms are rather ambiguous so let's avoid them. Maybe "full" > > watermark and "empty"? > > > > Unfortunately they are ambiguous to me. I know what the high watermark > is but not what the full or empty watermarks are. Really. So what's the "high" watermark? From the above text I'm thinking that you mean the high watermark is when the queue has a small number of requests and the low watermark is when the queue has a large number of requests. I'd have thought that this is backwards: the "high" watermark is when the queue has a large (ie: high) number of requests. A problem. How do we fix it? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org