From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qc0-f169.google.com (mail-qc0-f169.google.com [209.85.216.169]) by kanga.kvack.org (Postfix) with ESMTP id D32EE6B005A for ; Tue, 6 May 2014 13:25:20 -0400 (EDT) Received: by mail-qc0-f169.google.com with SMTP id e16so7281719qcx.0 for ; Tue, 06 May 2014 10:25:20 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTP id t1si5441390qap.230.2014.05.06.10.25.18 for ; Tue, 06 May 2014 10:25:18 -0700 (PDT) Message-ID: <53691AF9.7080608@redhat.com> Date: Tue, 06 May 2014 13:25:13 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH 07/17] mm: page_alloc: Take the ALLOC_NO_WATERMARK check out of the fast path References: <1398933888-4940-1-git-send-email-mgorman@suse.de> <1398933888-4940-8-git-send-email-mgorman@suse.de> In-Reply-To: <1398933888-4940-8-git-send-email-mgorman@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman , Linux-MM , Linux-FSDevel Cc: Johannes Weiner , Vlastimil Babka , Jan Kara , Michal Hocko , Hugh Dickins , Linux Kernel On 05/01/2014 04:44 AM, 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 Reviewed-by: Rik van Riel -- All rights reversed -- 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