From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [RFC] 0/4 Migration Cache Overview From: Lee Schermerhorn Reply-To: lee.schermerhorn@hp.com In-Reply-To: References: <1140190593.5219.22.camel@localhost.localdomain> <1140195598.5219.77.camel@localhost.localdomain> <43FA8690.3070608@yahoo.com.au> <20060221184016.GA19696@dmt.cnet> Content-Type: text/plain Date: Tue, 21 Feb 2006 13:49:51 -0500 Message-Id: <1140547791.5207.21.camel@localhost.localdomain> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Marcelo Tosatti , Nick Piggin , linux-mm List-ID: On Tue, 2006-02-21 at 10:04 -0800, Christoph Lameter wrote: > On Tue, 21 Feb 2006, Marcelo Tosatti wrote: > > > The idea was to create a "partition" inside the swapcache which allows > > for mapping+offset->pfn translation _without_ actually occupying space > > in the swap map (an idr table is used instead). > > > > But apparently Christoph's mechanism adds the PFN number into > > the page table entry itself, thus fulfilling the requirement for > > "mapping+offset"->pfn indexing required for removal of pages underneath > > a living process. Is that right? > > Right. Swap ptes contain the index into swap space which I am using to > preserve the information contained in the pte's of anonymous pages. Thus > the existing swap ptes couild be used. There were just a few minor > modifications to the swap functions required. > Are the swap ptes used for migrating pages still reserving swap space on real swap devices? I thought this was what the migration cache was trying to avoid. Now each running instance of direct migration limits itself to MIGRATE_CHUNK_SIZE [currently] 256 pages, so if the system has much swap space at all, this shouldn't place too much of a load on swap space. But, it does require that one have SOME swap space to migrate, right? Lee -- 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