From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 28 Aug 2007 14:54:19 -0700 (PDT) From: Christoph Lameter Subject: Re: RFC: Noreclaim with "Keep Mlocked Pages off the LRU" In-Reply-To: <1188312766.5079.77.camel@localhost> Message-ID: References: <20070823041137.GH18788@wotan.suse.de> <1187988218.5869.64.camel@localhost> <20070827013525.GA23894@wotan.suse.de> <1188225247.5952.41.camel@localhost> <20070828000648.GB14109@wotan.suse.de> <1188312766.5079.77.camel@localhost> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Lee Schermerhorn Cc: Nick Piggin , linux-mm , Rik van Riel List-ID: On Tue, 28 Aug 2007, Lee Schermerhorn wrote: > I didn't think I was special casing mlocked pages. I wanted to treat > all !page_reclaimable() pages the same--i.e., put them on the noreclaim > list. I think that is the right approach. Do not forget that ramfs and other ram based filesystems create unmapped unreclaimable pages. > Well, no. Depending on the reason for !reclaimable, the page would go > on the noreclaim list or just be dropped--special handling. More > importantly [for me], we still have to handle them specially in > migration, dumping them back onto the LRU so that we can arbitrate > access. If I'm ever successful in getting automatic/lazy page migration > +replication accepted, I don't want that overhead in > auto-migration/replication. Right. I posted a patch a week ago that generalized LRU handling and would allow the adding of additional lists as needed by such an approach. > If we're willing to live with this [increased rmap scans on mlocked > pages], we might be able to dispense with the mlock count altogether. > Just a single flag [somewhere--doesn't need to be in page flags member] > to indicate mlocked for page_reclaimable(). munmap()/munlock() could > reset the bit and put the page back on the [in]active list. If some > other vma has it locked, we'll catch it on next attempt to unmap. You need a page flag to indicate the fact that the page is on the unreclaimable list. -- 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