From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f200.google.com (mail-wr0-f200.google.com [209.85.128.200]) by kanga.kvack.org (Postfix) with ESMTP id E156C6B0333 for ; Mon, 27 Mar 2017 09:32:14 -0400 (EDT) Received: by mail-wr0-f200.google.com with SMTP id i18so16592815wrb.21 for ; Mon, 27 Mar 2017 06:32:14 -0700 (PDT) Received: from outbound-smtp09.blacknight.com (outbound-smtp09.blacknight.com. [46.22.139.14]) by mx.google.com with ESMTPS id v22si791180wra.229.2017.03.27.06.32.13 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 27 Mar 2017 06:32:13 -0700 (PDT) Received: from mail.blacknight.com (pemlinmail04.blacknight.ie [81.17.254.17]) by outbound-smtp09.blacknight.com (Postfix) with ESMTPS id 07F1C1C2161 for ; Mon, 27 Mar 2017 14:32:13 +0100 (IST) Date: Mon, 27 Mar 2017 14:32:12 +0100 From: Mel Gorman Subject: Re: Page allocator order-0 optimizations merged Message-ID: <20170327133212.6azfgrariwocdzzd@techsingularity.net> References: <83a0e3ef-acfa-a2af-2770-b9a92bda41bb@mellanox.com> <20170322234004.kffsce4owewgpqnm@techsingularity.net> <20170323144347.1e6f29de@redhat.com> <20170323145133.twzt4f5ci26vdyut@techsingularity.net> <779ab72d-94b9-1a28-c192-377e91383b4e@gmail.com> <1fc7338f-2b36-75f7-8a7e-8321f062207b@gmail.com> <2123321554.7161128.1490599967015.JavaMail.zimbra@redhat.com> <20170327105514.1ed5b1ba@redhat.com> <20170327143947.4c237e54@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20170327143947.4c237e54@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Jesper Dangaard Brouer Cc: Pankaj Gupta , Tariq Toukan , Tariq Toukan , netdev@vger.kernel.org, akpm@linux-foundation.org, linux-mm , Saeed Mahameed On Mon, Mar 27, 2017 at 02:39:47PM +0200, Jesper Dangaard Brouer wrote: > On Mon, 27 Mar 2017 10:55:14 +0200 > Jesper Dangaard Brouer wrote: > > > A possible solution, would be use the local_bh_{disable,enable} instead > > of the {preempt_disable,enable} calls. But it is slower, using numbers > > from [1] (19 vs 11 cycles), thus the expected cycles saving is 38-19=19. > > > > The problematic part of using local_bh_enable is that this adds a > > softirq/bottom-halves rescheduling point (as it checks for pending > > BHs). Thus, this might affects real workloads. > > I implemented this solution in patch below... and tested it on mlx5 at > 50G with manually disabled driver-page-recycling. It works for me. > > To Mel, that do you prefer... a partial-revert or something like this? > If Tariq confirms it works for him as well, this looks far safer patch than having a dedicate IRQ-safe queue. Your concern about the BH scheduling point is valid but if it's proven to be a problem, there is still the option of a partial revert. -- Mel Gorman SUSE Labs -- 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