From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 28 Aug 2007 01:51:53 +0200 From: Nick Piggin Subject: Re: RFC: Noreclaim with "Keep Mlocked Pages off the LRU" Message-ID: <20070827235153.GA14109@wotan.suse.de> References: <20070823041137.GH18788@wotan.suse.de> <1187988218.5869.64.camel@localhost> <20070827013525.GA23894@wotan.suse.de> <1188225247.5952.41.camel@localhost> <20070827154426.GA27868@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070827154426.GA27868@infradead.org> Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Hellwig Cc: Lee Schermerhorn , linux-mm , Rik van Riel List-ID: On Mon, Aug 27, 2007 at 04:44:26PM +0100, Christoph Hellwig wrote: > On Mon, Aug 27, 2007 at 10:34:07AM -0400, Lee Schermerhorn wrote: > > Well, keeping the mlock count in the lru pointer more or less defeats > > the purpose of this exercise for me--that is, a unified mechanism for > > tracking "non-reclaimable" pages. I wanted to maintain the ability to > > use the zone lru_lock and isolate_lru_page() to arbitrate access to > > pages for migration, etc. w/o having to temporarily put the pages back > > on the lru during migration. > > A few years ago I tried to implement a mlocked counter in the page > aswell, and my approach was to create a union to reuse the space occupied > by the lru list pointers for this. I never really got it stable enough > because people tripped over the lru list randomly far too often. My original mlock patches that Lee is talking about did use your method. I _believe_ it is basically bug free and worked nicely. These days we're a bit more consistent and have fewer races with LRU handling, which is perhaps what made it doable. -- 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