Re: [PATCH v3 net-next 08/14] mlx4: use order-0 pages for RX
From: Jesper Dangaard Brouer <hidden>
Date: 2017-02-14 20:02:27
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linux-mm
On Tue, 14 Feb 2017 11:02:01 -0800 Eric Dumazet [off-list ref] wrote:
On Tue, Feb 14, 2017 at 10:46 AM, Jesper Dangaard Brouer [off-list ref] wrote:quoted
quoted
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 [off-list ref] 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