From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f72.google.com (mail-oi0-f72.google.com [209.85.218.72]) by kanga.kvack.org (Postfix) with ESMTP id 8B041680FD0 for ; Tue, 14 Feb 2017 15:02:27 -0500 (EST) Received: by mail-oi0-f72.google.com with SMTP id u143so205105246oif.1 for ; Tue, 14 Feb 2017 12:02:27 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id u72si1895805itb.65.2017.02.14.12.02.26 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 14 Feb 2017 12:02:26 -0800 (PST) Date: Tue, 14 Feb 2017 21:02:19 +0100 From: Jesper Dangaard Brouer Subject: Re: [PATCH v3 net-next 08/14] mlx4: use order-0 pages for RX Message-ID: <20170214210219.1ea87229@redhat.com> In-Reply-To: References: <20170213195858.5215-1-edumazet@google.com> <20170213195858.5215-9-edumazet@google.com> <20170214131206.44b644f6@redhat.com> <20170214194615.3feddd07@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Eric Dumazet Cc: Alexander Duyck , Tariq Toukan , "David S . Miller" , netdev , Tariq Toukan , Martin KaFai Lau , Saeed Mahameed , Willem de Bruijn , Brenden Blanco , Alexei Starovoitov , Eric Dumazet , linux-mm , brouer@redhat.com On Tue, 14 Feb 2017 11:02:01 -0800 Eric Dumazet wrote: > On Tue, Feb 14, 2017 at 10:46 AM, Jesper Dangaard Brouer > wrote: > > > > > > > With this Intel driver page count based recycle approach, the recycle > > size is tied to the size of the RX ring. As Eric and Tariq discovered. > > And for other performance reasons (memory footprint of walking RX ring > > data-structures), don't want to increase the RX ring sizes. Thus, it > > create two opposite performance needs. That is why I think a more > > explicit approach with a pool is more attractive. > > > > How is this approach doing to work for XDP? > > (XDP doesn't "share" the page, and in-general we don't want the extra > > atomic.) > > > > We absolutely need recycling with XDP, when transmitting out another > > device, and the other devices DMA-TX completion need some way of > > returning this page. > > What is basically needed is a standardized callback to allow the remote > > driver to return the page to the originating driver. As we don't have > > a NDP for XDP-forward/transmit yet, we could pass this callback as a > > parameter along with the packet-page to send? > > > > > > > mlx4 already has a cache for XDP. > I believe I did not change this part, it still should work. > > commit d576acf0a22890cf3f8f7a9b035f1558077f6770 > Author: Brenden Blanco > Date: Tue Jul 19 12:16:52 2016 -0700 > > net/mlx4_en: add page recycle to prepare rx ring for tx support This obviously does not work for the case I'm talking about (transmitting out another device with XDP). -- 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