From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754690Ab3LQWbt (ORCPT ); Tue, 17 Dec 2013 17:31:49 -0500 Received: from zene.cmpxchg.org ([85.214.230.12]:50296 "EHLO zene.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752020Ab3LQWbr (ORCPT ); Tue, 17 Dec 2013 17:31:47 -0500 Date: Tue, 17 Dec 2013 17:31:36 -0500 From: Johannes Weiner To: Mel Gorman Cc: Andrew Morton , Dave Hansen , Rik van Riel , Linux-MM , LKML Subject: Re: [PATCH 3/7] mm: page_alloc: Use zone node IDs to approximate locality Message-ID: <20131217223136.GI21724@cmpxchg.org> References: <1386943807-29601-1-git-send-email-mgorman@suse.de> <1386943807-29601-4-git-send-email-mgorman@suse.de> <20131216202507.GZ21724@cmpxchg.org> <20131217111352.GZ11295@suse.de> <20131217153829.GC21724@cmpxchg.org> <20131217160808.GF11295@suse.de> <20131217201147.GH21724@cmpxchg.org> <20131217210340.GJ11295@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131217210340.GJ11295@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 17, 2013 at 09:03:40PM +0000, Mel Gorman wrote: > On Tue, Dec 17, 2013 at 03:11:47PM -0500, Johannes Weiner wrote: > > On Tue, Dec 17, 2013 at 04:08:08PM +0000, Mel Gorman wrote: > > > On Tue, Dec 17, 2013 at 10:38:29AM -0500, Johannes Weiner wrote: > > > > On Tue, Dec 17, 2013 at 11:13:52AM +0000, Mel Gorman wrote: > > > > > On Mon, Dec 16, 2013 at 03:25:07PM -0500, Johannes Weiner wrote: > > > > > > On Fri, Dec 13, 2013 at 02:10:03PM +0000, Mel Gorman wrote: > > > > > > > zone_local is using node_distance which is a more expensive call than > > > > > > > necessary. On x86, it's another function call in the allocator fast path > > > > > > > and increases cache footprint. This patch makes the assumption zones on a > > > > > > > local node will share the same node ID. The necessary information should > > > > > > > already be cache hot. > > > > > > > > > > > > > > Signed-off-by: Mel Gorman > > > > > > > --- > > > > > > > mm/page_alloc.c | 2 +- > > > > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > > > > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > > > > > > index 64020eb..fd9677e 100644 > > > > > > > --- a/mm/page_alloc.c > > > > > > > +++ b/mm/page_alloc.c > > > > > > > @@ -1816,7 +1816,7 @@ static void zlc_clear_zones_full(struct zonelist *zonelist) > > > > > > > > > > > > > > static bool zone_local(struct zone *local_zone, struct zone *zone) > > > > > > > { > > > > > > > - return node_distance(local_zone->node, zone->node) == LOCAL_DISTANCE; > > > > > > > + return zone_to_nid(zone) == numa_node_id(); > > > > > > > > > > > > Why numa_node_id()? We pass in the preferred zone as @local_zone: > > > > > > > > > > > > > > > > Initially because I was thinking "local node" and numa_node_id() is a > > > > > per-cpu variable that should be cheap to access and in some cases > > > > > cache-hot as the top-level gfp API calls numa_node_id(). > > > > > > > > > > Thinking about it more though it still makes sense because the preferred > > > > > zone is not necessarily local. If the allocation request requires ZONE_DMA32 > > > > > and the local node does not have that zone then preferred zone is on a > > > > > remote node. > > > > > > > > Don't we treat everything in relation to the preferred zone? > > > > > > Usually yes, but this time we really care about whether the memory is > > > local or remote. It makes sense to me as it is and struggle to see an > > > advantage of expressing it in terms of the preferred zone. Minimally > > > zone_local would need to be renamed if it could return true for a remote > > > zone and I see no advantage in doing that. > > > > What the function tests for is whether any given zone is close > > enough/local to the given preferred zone such that we can allocate > > from it without having to invoke zone_reclaim_mode. > > > > Fine. The helper should then be renamed to zone_preferred_node because > it's no longer about being local. Fair enough! From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-bk0-f42.google.com (mail-bk0-f42.google.com [209.85.214.42]) by kanga.kvack.org (Postfix) with ESMTP id AB8A26B0035 for ; Tue, 17 Dec 2013 17:31:47 -0500 (EST) Received: by mail-bk0-f42.google.com with SMTP id w11so3133749bkz.1 for ; Tue, 17 Dec 2013 14:31:46 -0800 (PST) Received: from zene.cmpxchg.org (zene.cmpxchg.org. [2a01:238:4224:fa00:ca1f:9ef3:caee:a2bd]) by mx.google.com with ESMTPS id pf10si5730250bkb.249.2013.12.17.14.31.46 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Tue, 17 Dec 2013 14:31:46 -0800 (PST) Date: Tue, 17 Dec 2013 17:31:36 -0500 From: Johannes Weiner Subject: Re: [PATCH 3/7] mm: page_alloc: Use zone node IDs to approximate locality Message-ID: <20131217223136.GI21724@cmpxchg.org> References: <1386943807-29601-1-git-send-email-mgorman@suse.de> <1386943807-29601-4-git-send-email-mgorman@suse.de> <20131216202507.GZ21724@cmpxchg.org> <20131217111352.GZ11295@suse.de> <20131217153829.GC21724@cmpxchg.org> <20131217160808.GF11295@suse.de> <20131217201147.GH21724@cmpxchg.org> <20131217210340.GJ11295@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131217210340.GJ11295@suse.de> Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Andrew Morton , Dave Hansen , Rik van Riel , Linux-MM , LKML On Tue, Dec 17, 2013 at 09:03:40PM +0000, Mel Gorman wrote: > On Tue, Dec 17, 2013 at 03:11:47PM -0500, Johannes Weiner wrote: > > On Tue, Dec 17, 2013 at 04:08:08PM +0000, Mel Gorman wrote: > > > On Tue, Dec 17, 2013 at 10:38:29AM -0500, Johannes Weiner wrote: > > > > On Tue, Dec 17, 2013 at 11:13:52AM +0000, Mel Gorman wrote: > > > > > On Mon, Dec 16, 2013 at 03:25:07PM -0500, Johannes Weiner wrote: > > > > > > On Fri, Dec 13, 2013 at 02:10:03PM +0000, Mel Gorman wrote: > > > > > > > zone_local is using node_distance which is a more expensive call than > > > > > > > necessary. On x86, it's another function call in the allocator fast path > > > > > > > and increases cache footprint. This patch makes the assumption zones on a > > > > > > > local node will share the same node ID. The necessary information should > > > > > > > already be cache hot. > > > > > > > > > > > > > > Signed-off-by: Mel Gorman > > > > > > > --- > > > > > > > mm/page_alloc.c | 2 +- > > > > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > > > > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > > > > > > index 64020eb..fd9677e 100644 > > > > > > > --- a/mm/page_alloc.c > > > > > > > +++ b/mm/page_alloc.c > > > > > > > @@ -1816,7 +1816,7 @@ static void zlc_clear_zones_full(struct zonelist *zonelist) > > > > > > > > > > > > > > static bool zone_local(struct zone *local_zone, struct zone *zone) > > > > > > > { > > > > > > > - return node_distance(local_zone->node, zone->node) == LOCAL_DISTANCE; > > > > > > > + return zone_to_nid(zone) == numa_node_id(); > > > > > > > > > > > > Why numa_node_id()? We pass in the preferred zone as @local_zone: > > > > > > > > > > > > > > > > Initially because I was thinking "local node" and numa_node_id() is a > > > > > per-cpu variable that should be cheap to access and in some cases > > > > > cache-hot as the top-level gfp API calls numa_node_id(). > > > > > > > > > > Thinking about it more though it still makes sense because the preferred > > > > > zone is not necessarily local. If the allocation request requires ZONE_DMA32 > > > > > and the local node does not have that zone then preferred zone is on a > > > > > remote node. > > > > > > > > Don't we treat everything in relation to the preferred zone? > > > > > > Usually yes, but this time we really care about whether the memory is > > > local or remote. It makes sense to me as it is and struggle to see an > > > advantage of expressing it in terms of the preferred zone. Minimally > > > zone_local would need to be renamed if it could return true for a remote > > > zone and I see no advantage in doing that. > > > > What the function tests for is whether any given zone is close > > enough/local to the given preferred zone such that we can allocate > > from it without having to invoke zone_reclaim_mode. > > > > Fine. The helper should then be renamed to zone_preferred_node because > it's no longer about being local. Fair enough! -- 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