Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755006Ab1EPVQz (ORCPT ); Mon, 16 May 2011 17:16:55 -0400 Received: from smtp-out.google.com ([74.125.121.67]:46962 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754159Ab1EPVQx (ORCPT ); Mon, 16 May 2011 17:16:53 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version:content-type; b=snMmZmsxrTNnAZQOc94OdmF41k+pBvJXstArln+VUaY4NYj/2uqc12hn2fDZfsrIps sEb7Fe/lZiPvaN+8bCOA== Date: Mon, 16 May 2011 14:16:46 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Mel Gorman cc: Andrew Morton , James Bottomley , Colin King , Raghavendra D Prabhu , Jan Kara , Chris Mason , Christoph Lameter , Pekka Enberg , Rik van Riel , Johannes Weiner , linux-fsdevel , linux-mm , linux-kernel , linux-ext4 Subject: Re: [PATCH 3/4] mm: slub: Do not take expensive steps for SLUBs speculative high-order allocations In-Reply-To: <1305295404-12129-4-git-send-email-mgorman@suse.de> Message-ID: References: <1305295404-12129-1-git-send-email-mgorman@suse.de> <1305295404-12129-4-git-send-email-mgorman@suse.de> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2052 Lines: 50 On Fri, 13 May 2011, Mel Gorman wrote: > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 9f8a97b..057f1e2 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1972,6 +1972,7 @@ gfp_to_alloc_flags(gfp_t gfp_mask) > { > int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET; > const gfp_t wait = gfp_mask & __GFP_WAIT; > + const gfp_t can_wake_kswapd = !(gfp_mask & __GFP_NO_KSWAPD); > > /* __GFP_HIGH is assumed to be the same as ALLOC_HIGH to save a branch. */ > BUILD_BUG_ON(__GFP_HIGH != (__force gfp_t) ALLOC_HIGH); > @@ -1984,7 +1985,7 @@ gfp_to_alloc_flags(gfp_t gfp_mask) > */ > alloc_flags |= (__force int) (gfp_mask & __GFP_HIGH); > > - if (!wait) { > + if (!wait && can_wake_kswapd) { > /* > * Not worth trying to allocate harder for > * __GFP_NOMEMALLOC even if it can't schedule. > diff --git a/mm/slub.c b/mm/slub.c > index 98c358d..c5797ab 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -1170,7 +1170,8 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node) > * Let the initial higher-order allocation fail under memory pressure > * so we fall-back to the minimum order allocation. > */ > - alloc_gfp = (flags | __GFP_NOWARN | __GFP_NORETRY | __GFP_NO_KSWAPD) & ~__GFP_NOFAIL; > + alloc_gfp = (flags | __GFP_NOWARN | __GFP_NO_KSWAPD) & > + ~(__GFP_NOFAIL | __GFP_WAIT | __GFP_REPEAT); > > page = alloc_slab_page(alloc_gfp, node, oo); > if (unlikely(!page)) { It's unnecessary to clear __GFP_REPEAT, these !__GFP_NOFAIL allocations will immediately fail. alloc_gfp would probably benefit from having a comment about why __GFP_WAIT should be masked off here: that we don't want to do compaction or direct reclaim or retry the allocation more than once (so both __GFP_NORETRY and __GFP_REPEAT are no-ops). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/