From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesper Dangaard Brouer Subject: Re: Page allocator order-0 optimizations merged Date: Tue, 28 Mar 2017 20:24:26 +0200 Message-ID: <20170328202426.6485bd91@redhat.com> 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> <20170327133212.6azfgrariwocdzzd@techsingularity.net> <0873b65b-2217-005d-0b42-4af6ad66cc0f@gmail.com> <26c4d7a4-c8a7-fbad-d2be-a5a90f6d93d3@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Mel Gorman , Pankaj Gupta , Tariq Toukan , netdev@vger.kernel.org, akpm@linux-foundation.org, linux-mm , Saeed Mahameed , brouer@redhat.com To: Tariq Toukan Return-path: In-Reply-To: <26c4d7a4-c8a7-fbad-d2be-a5a90f6d93d3@gmail.com> Sender: owner-linux-mm@kvack.org List-Id: netdev.vger.kernel.org On Tue, 28 Mar 2017 19:05:12 +0300 Tariq Toukan wrote: > On 28/03/2017 10:32 AM, Tariq Toukan wrote: > > > > > > On 27/03/2017 4:32 PM, Mel Gorman wrote: > >> 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 > > > > Great. > > I will test Jesper's patch today in the afternoon. > > > > It looks very good! > I get line-rate (94Gbits/sec) with 8 streams, in comparison to less than > 55Gbits/sec before. Just confirming, this is when you have disabled mlx5 driver page-recycling, right? > >> 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. -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer -- 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