From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx206.postini.com [74.125.245.206]) by kanga.kvack.org (Postfix) with SMTP id 1E8AA6B0038 for ; Mon, 5 Aug 2013 15:44:50 -0400 (EDT) Date: Mon, 5 Aug 2013 15:44:44 -0400 From: Johannes Weiner Subject: Re: [PATCH 4/9] mm: zone_reclaim: compaction: reset before initializing the scan cursors Message-ID: <20130805194444.GD1845@cmpxchg.org> References: <1375459596-30061-1-git-send-email-aarcange@redhat.com> <1375459596-30061-5-git-send-email-aarcange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1375459596-30061-5-git-send-email-aarcange@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrea Arcangeli Cc: linux-mm@kvack.org, Johannes Weiner , Mel Gorman , Rik van Riel , Hugh Dickins , Richard Davies , Shaohua Li , Rafael Aquini , Andrew Morton , Hush Bensen On Fri, Aug 02, 2013 at 06:06:31PM +0200, Andrea Arcangeli wrote: > Correct the location where we reset the scan cursors, otherwise the > first iteration of compaction (after restarting it) will only do a > partial scan. > > Signed-off-by: Andrea Arcangeli > Reviewed-by: Rik van Riel > Acked-by: Mel Gorman > Acked-by: Rafael Aquini Acked-by: Johannes Weiner Yes, it does not make sense to read the situation from the cache first, then two lines later invalidate it because it's stale data. That being said, why are we maintaining the pageblock skip bits in addition to the scanner offset caches? Sometimes we only set the pageblock skip bit and not update the position cache, but the next invocation will skip over these blocks anyway because of !isolation_suitable(). And they are invalidated together. Aren't they redundant? -- 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