From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mel Gorman Subject: Re: [PATCH net-next V2 05/11] net/mlx5e: Support RX multi-packet WQE (Striding RQ) Date: Tue, 19 Apr 2016 18:39:26 +0100 Message-ID: <20160419173833.GB15167@techsingularity.net> References: <1460928725-18741-1-git-send-email-saeedm@mellanox.com> <1460928725-18741-6-git-send-email-saeedm@mellanox.com> <1460939371.10638.97.camel@edumazet-glaptop3.roam.corp.google.com> <1460983695.10638.113.camel@edumazet-glaptop3.roam.corp.google.com> <1460989033.10638.120.camel@edumazet-glaptop3.roam.corp.google.com> <20160419182532.423d3c05@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Cc: Eric Dumazet , Saeed Mahameed , Saeed Mahameed , "David S. Miller" , Linux Netdev List , Or Gerlitz , Tal Alon , Tariq Toukan , Eran Ben Elisha , Achiad Shochat , linux-mm To: Jesper Dangaard Brouer Return-path: Content-Disposition: inline In-Reply-To: <20160419182532.423d3c05@redhat.com> Sender: owner-linux-mm@kvack.org List-Id: netdev.vger.kernel.org On Tue, Apr 19, 2016 at 06:25:32PM +0200, Jesper Dangaard Brouer wrote: > On Mon, 18 Apr 2016 07:17:13 -0700 > Eric Dumazet wrote: > > > On Mon, 2016-04-18 at 16:05 +0300, Saeed Mahameed wrote: > > > On Mon, Apr 18, 2016 at 3:48 PM, Eric Dumazet wrote: > > > > On Sun, 2016-04-17 at 17:29 -0700, Eric Dumazet wrote: > > > > > > > >> > > > >> If really you need to allocate physically contiguous memory, have you > > > >> considered converting the order-5 pages into 32 order-0 ones ? > > > > > > > > Search for split_page() call sites for examples. > > > > > > > > > > > > > > Thanks Eric, we are already evaluating split_page as we speak. > > > > > > We did look but could not find any specific alloc_pages API that alloc_pages_exact() > > > allocates many physically contiguous pages with order0 ! so we assume > > > it is ok to use split_page. > > > > Note: I have no idea of split_page() performance : > > Maybe Mel knows? Irrelevant in comparison to the cost of allocating an order-5 pages if one is not already available. > And maybe Mel have an opinion about if this is a good > or bad approach, e.g. will this approach stress the page allocator in a > bad way? > It'll contend on the zone lock minimally but again, irrelevant in comparison to having to reclaim/compact an order-5 page if one is not already free. It'll appear to work well in benchmarks and then fall apart when the system is running for long enough. -- 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