From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <426470EB.4090600@sgi.com> Date: Mon, 18 Apr 2005 21:46:03 -0500 From: Ray Bryant MIME-Version: 1.0 Subject: Re: question on page-migration code References: <425AC268.4090704@engr.sgi.com> <20050412.084143.41655902.taka@valinux.co.jp> <1113324392.8343.53.camel@localhost> <20050413.194800.74725991.taka@valinux.co.jp> In-Reply-To: <20050413.194800.74725991.taka@valinux.co.jp> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Hirokazu Takahashi Cc: haveblue@us.ibm.com, raybry@engr.sgi.com, marcelo.tosatti@cyclades.com, linux-mm@kvack.org List-ID: Hirokazu et al, I'm sorry, I've been kind of out of the loop here since last Wenesday (that's the day I left Austin to fly to Melbourne, Australia which is where I am now, visiting the SGI lab in Melbourne). Nathan Scott (who works at SGI Melbourne) looked at the ext2/ext3 migrate_page code and realized that basically the same implementation would work for xfs. So I now have a kernel that implements that function for xfs and, as you predicted, the "slow down" in the 2nd migration that I was seeing before has gone away. I'll add Nathan's patch to my manual page migration stuff in the next version (later this week, I hope). So I guess it doesn't matter to me at the moment whether or not the PG_dirty bit is set on the pages, except that I philosphically dislike the fact that migration changes the state of the page. I'm not sure it matters, but I would prefer it if this didn't happen. However, I'm not adamant about this, since what I really want to happen is to have a functioning manual page migration system call. It does seem to be a bother to have to add that migrate_page method to each file system, since in most cases the addition is going to look somewhat like it does for ext2/3. For xfs, Nathan did add an additional bit to make sure that xfs metadata pages were not considered migratable. WRT, Marcelo's question as to who is causing the page out I/O to occur during migration, let me go back and verify this is actually what is happening. Otherwise, is there a consensus about what to do about the PG_dirty bits being set on the migrated pages? As I read things Marcelo says it is not worth it, but others think that it should be fixed? -- ----------------------------------------------- Ray Bryant 512-453-9679 (work) 512-507-7807 (cell) raybry@sgi.com raybry@austin.rr.com The box said: "Requires Windows 98 or better", so I installed Linux. ----------------------------------------------- -- 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: aart@kvack.org