From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx174.postini.com [74.125.245.174]) by kanga.kvack.org (Postfix) with SMTP id 2E7DC6B0031 for ; Tue, 6 Aug 2013 01:50:57 -0400 (EDT) Date: Tue, 6 Aug 2013 07:50:40 +0200 From: Andrea Arcangeli Subject: Re: [PATCH 2/9] mm: zone_reclaim: compaction: scan all memory with /proc/sys/vm/compact_memory Message-ID: <20130806055040.GD15161@redhat.com> References: <1375459596-30061-1-git-send-email-aarcange@redhat.com> <1375459596-30061-3-git-send-email-aarcange@redhat.com> <20130805184559.GB1845@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130805184559.GB1845@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: linux-mm@kvack.org, Johannes Weiner , Mel Gorman , Rik van Riel , Hugh Dickins , Richard Davies , Shaohua Li , Rafael Aquini , Andrew Morton , Hush Bensen Hi! On Mon, Aug 05, 2013 at 02:45:59PM -0400, Johannes Weiner wrote: > On Fri, Aug 02, 2013 at 06:06:29PM +0200, Andrea Arcangeli wrote: > > Reset the stats so /proc/sys/vm/compact_memory will scan all memory. > > > > Signed-off-by: Andrea Arcangeli > > Reviewed-by: Rik van Riel > > Acked-by: Rafael Aquini > > Acked-by: Mel Gorman > > It somehow feels wrong that this operation should have a destructive > side effect, rather than just ignore the cached info for the one run > (like cc.ignore_skip_hint). But I don't really have a strong reason > against it, so... But what benefit would provide to keep the cached cursor positions alive after we already compacted the whole memory from the start to the end? The cached cursors provide useful information when we compact in small steps and they represent the unscanned part of the memory. But after a full compaction completed unless some memory activity has happened there will be nothing to compact anymore. So we just need to find what may have changed as result of the memory activity and in turn there should be no benefit in starting at the previously cached cursors positions. > > Acked-by: Johannes Weiner Thanks! Andrea -- 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