From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id 7ECCA6B021B for ; Thu, 29 Apr 2010 23:52:41 -0400 (EDT) Date: Fri, 30 Apr 2010 05:52:38 +0200 (CEST) From: Mikulas Patocka Subject: Re: swapping when there's a free memory In-Reply-To: <20100427103517.ae0658cf.kamezawa.hiroyu@jp.fujitsu.com> Message-ID: References: <20100425071349.GA1275@ucw.cz> <20100426153333.93c03e98.akpm@linux-foundation.org> <20100427103517.ae0658cf.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Andrew Morton , Pavel Machek , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Tue, 27 Apr 2010, KAMEZAWA Hiroyuki wrote: > On Mon, 26 Apr 2010 15:33:33 -0700 > Andrew Morton wrote: > > > On Sun, 25 Apr 2010 09:13:49 +0200 > > Pavel Machek wrote: > > > > > Hi! > > > > > > > I captured this output of vmstat. The machine was freeing cache and > > > > swapping out pages even when there was a plenty of free memory. > > > > > > > > The machine is sparc64 with 1GB RAM with 2.6.34-rc4. This abnormal > > > > swapping happened during running spadfsck --- a fsck program for a custom > > > > filesystem that caches most reads in its internal cache --- so it reads > > > > buffers and allocates memory at the same time. > > > > > > > > Note that sparc64 doesn't have any low/high memory zones, so it couldn't > > > > be explained by filling one zone and needing to allocate pages in it. > > > > > > Fragmented memory + high-order allocation? > > > > Yeah, could be. I wonder which slab/slub/slob implementation you're > > using, and what page sizes it uses for dentries, inodes, etc. Can you > > have a poke in /prob/slabinfo? It uses one page-per-slab for dentries and two for inodes. But there was certainly no dentry or inode-based load --- the machine runs without X with minimum daemons, there is no major background work. There was just a process reading 128-kbyte blocks from a raw device and caching them in its userspace that triggered this. Can it be that kernel uses high-order allocations for reading from a buffer cache? > And please /proc/buddyinfo and /proc/zoneinfo when the system is swappy. It happens rarely, I don't know if I catch it at the right time. The report I sent, was what I found in a scrollback of vmstat. I didn't catch it in real time. > Thanks, > -Kame Mikulas -- 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