From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ee0-f47.google.com (mail-ee0-f47.google.com [74.125.83.47]) by kanga.kvack.org (Postfix) with ESMTP id 250F96B0038 for ; Fri, 18 Apr 2014 14:10:23 -0400 (EDT) Received: by mail-ee0-f47.google.com with SMTP id b15so1838092eek.20 for ; Fri, 18 Apr 2014 11:10:22 -0700 (PDT) Received: from zene.cmpxchg.org (zene.cmpxchg.org. [2a01:238:4224:fa00:ca1f:9ef3:caee:a2bd]) by mx.google.com with ESMTPS id x47si41377139eel.13.2014.04.18.11.10.21 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Fri, 18 Apr 2014 11:10:21 -0700 (PDT) Date: Fri, 18 Apr 2014 14:10:19 -0400 From: Johannes Weiner Subject: Re: [PATCH 09/16] mm: page_alloc: Take the ALLOC_NO_WATERMARK check out of the fast path Message-ID: <20140418181019.GF29210@cmpxchg.org> References: <1397832643-14275-1-git-send-email-mgorman@suse.de> <1397832643-14275-10-git-send-email-mgorman@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1397832643-14275-10-git-send-email-mgorman@suse.de> Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Linux-MM , Linux-FSDevel On Fri, Apr 18, 2014 at 03:50:36PM +0100, Mel Gorman wrote: > ALLOC_NO_WATERMARK is set in a few cases. Always by kswapd, always for > __GFP_MEMALLOC, sometimes for swap-over-nfs, tasks etc. Each of these cases > are relatively rare events but the ALLOC_NO_WATERMARK check is an unlikely > branch in the fast path. This patch moves the check out of the fast path > and after it has been determined that the watermarks have not been met. This > helps the common fast path at the cost of making the slow path slower and > hitting kswapd with a performance cost. It's a reasonable tradeoff. > > Signed-off-by: Mel Gorman Acked-by: Johannes Weiner -- 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