From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 6 Nov 2007 19:02:47 -0800 (PST) From: Christoph Lameter Subject: Re: [RFC PATCH 3/10] define page_file_cache In-Reply-To: <20071106215552.4ab7df81@bree.surriel.com> Message-ID: References: <20071103184229.3f20e2f0@bree.surriel.com> <20071103185516.24832ab0@bree.surriel.com> <20071106215552.4ab7df81@bree.surriel.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Rik van Riel Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Tue, 6 Nov 2007, Rik van Riel wrote: > > I think we could add a flag to the bdi to indicate wheter the backing > > store is a disk file. In fact you can also deduce if if a device has > > no writeback capability set in the BDI. > > > > > Unfortunately this needs to use a page flag, since the > > > PG_swapbacked state needs to be preserved all the way > > > to the point where the page is last removed from the > > > LRU. Trying to derive the status from other info in > > > the page resulted in wrong VM statistics in earlier > > > split VM patchsets. > > > > The bdi may avoid that extra flag. > > The bdi will no longer be accessible by the time a page > makes it to free_hot_cold_page, which is one place in the > kernel where this information is needed. At that point you need only information about which list the page was put on. Dont we need something like PageLRU -> PageFileLRU and PageMemLRU? The page may change its nature I think? What if a page becomes swap backed? -- 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