From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx107.postini.com [74.125.245.107]) by kanga.kvack.org (Postfix) with SMTP id C46FF6B0005 for ; Thu, 11 Apr 2013 06:29:45 -0400 (EDT) Received: by mail-qe0-f53.google.com with SMTP id q19so798160qeb.12 for ; Thu, 11 Apr 2013 03:29:44 -0700 (PDT) Message-ID: <51669091.5070406@gmail.com> Date: Thu, 11 Apr 2013 18:29:37 +0800 From: Ric Mason MIME-Version: 1.0 Subject: Re: [PATCH 08/10] mm: vmscan: Have kswapd shrink slab only once per priority References: <1363525456-10448-1-git-send-email-mgorman@suse.de> <1363525456-10448-9-git-send-email-mgorman@suse.de> <20130409065325.GA4411@lge.com> <20130409111358.GB2002@suse.de> <20130410052142.GB5872@lge.com> <20130411100115.GJ3710@suse.de> In-Reply-To: <20130411100115.GJ3710@suse.de> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Joonsoo Kim , Linux-MM , Jiri Slaby , Valdis Kletnieks , Rik van Riel , Zlatko Calusic , Johannes Weiner , dormando , Satoru Moriya , Michal Hocko , LKML Hi Mel, On 04/11/2013 06:01 PM, Mel Gorman wrote: > On Wed, Apr 10, 2013 at 02:21:42PM +0900, Joonsoo Kim wrote: >>>>> @@ -2673,9 +2674,15 @@ static bool kswapd_shrink_zone(struct zone *zone, >>>>> sc->nr_to_reclaim = max(SWAP_CLUSTER_MAX, high_wmark_pages(zone)); >>>>> shrink_zone(zone, sc); >>>>> >>>>> - reclaim_state->reclaimed_slab = 0; >>>>> - nr_slab = shrink_slab(&shrink, sc->nr_scanned, lru_pages); >>>>> - sc->nr_reclaimed += reclaim_state->reclaimed_slab; >>>>> + /* >>>>> + * Slabs are shrunk for each zone once per priority or if the zone >>>>> + * being balanced is otherwise unreclaimable >>>>> + */ >>>>> + if (shrinking_slab || !zone_reclaimable(zone)) { >>>>> + reclaim_state->reclaimed_slab = 0; >>>>> + nr_slab = shrink_slab(&shrink, sc->nr_scanned, lru_pages); >>>>> + sc->nr_reclaimed += reclaim_state->reclaimed_slab; >>>>> + } >>>>> >>>>> if (nr_slab == 0 && !zone_reclaimable(zone)) >>>>> zone->all_unreclaimable = 1; >>>> Why shrink_slab() is called here? >>> Preserves existing behaviour. >> Yes, but, with this patch, existing behaviour is changed, that is, we call >> shrink_slab() once per priority. For now, there is no reason this function >> is called here. How about separating it and executing it outside of >> zone loop? >> > We are calling it fewer times but it's still receiving the same information > from sc->nr_scanned it received before. With the change you are suggesting > it would be necessary to accumulating sc->nr_scanned for each zone shrunk > and then pass the sum to shrink_slab() once per priority. While this is not > necessarily wrong, there is little or no motivation to alter the shrinkers > in this manner in this series. Why the result is not the same? -- 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