From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f199.google.com (mail-qt0-f199.google.com [209.85.216.199]) by kanga.kvack.org (Postfix) with ESMTP id 6CA496B039F for ; Tue, 28 Mar 2017 04:28:57 -0400 (EDT) Received: by mail-qt0-f199.google.com with SMTP id 30so48884916qtw.19 for ; Tue, 28 Mar 2017 01:28:57 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id d68si2897297qkg.136.2017.03.28.01.28.56 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 28 Mar 2017 01:28:56 -0700 (PDT) Date: Tue, 28 Mar 2017 04:28:51 -0400 (EDT) From: Pankaj Gupta Message-ID: <880114946.7747224.1490689731036.JavaMail.zimbra@redhat.com> In-Reply-To: <20170327133212.6azfgrariwocdzzd@techsingularity.net> References: <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> <20170327133212.6azfgrariwocdzzd@techsingularity.net> Subject: Re: Page allocator order-0 optimizations merged MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Jesper Dangaard Brouer , 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. I also feel the same. Thanks, Pankaj > > -- > 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