From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: Active Memory Defragmentation: Our implementation & problems From: Dave Hansen In-Reply-To: <20040204185446.91810.qmail@web9705.mail.yahoo.com> References: <20040204185446.91810.qmail@web9705.mail.yahoo.com> Content-Type: text/plain Message-Id: <1075924593.27981.458.camel@nighthawk> Mime-Version: 1.0 Date: 04 Feb 2004 11:56:33 -0800 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Alok Mooley Cc: linux-kernel , linux-mm List-ID: On Wed, 2004-02-04 at 10:54, Alok Mooley wrote: > --- Dave Hansen wrote: > > > The "work until we get interrupted and restart if > > something changes > > state" approach is very, very common. Can you give > > some more examples > > of just how a page fault would ruin the defrag > > process? > > > > What I mean to say is that if we have identified some > pages for movement, & we get preempted, the pages > identified as movable may not remain movable any more > when we are rescheduled. We are left with the task of > identifying new movable pages. Depending on the quantity of work that you're trying to do at once, this might be unavoidable. I know it's a difficult thing to think about, but I still don't understand the precise cases that you're concerned about. Page faults to me seem like the least of your problems. A bigger issue would be if the page is written to by userspace after you copy, but before you install the new pte. Did I miss the code in your patch that invalidated the old tlb entries? --dave -- 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