On Thu, 7 Apr 2016 19:48:50 +0000 "Waskiewicz, PJ" <PJ.Waskiewicz@xxxxxxxxxx> wrote: > On Thu, 2016-04-07 at 16:17 +0200, Jesper Dangaard Brouer wrote: > > (Topic proposal for MM-summit) > > > > Network Interface Cards (NIC) drivers, and increasing speeds stress > > the page-allocator (and DMA APIs). A number of driver specific > > open-coded approaches exists that work-around these bottlenecks in > > the > > page allocator and DMA APIs. E.g. open-coded recycle mechanisms, and > > allocating larger pages and handing-out page "fragments". > > > > I'm proposing a generic page-pool recycle facility, that can cover > > the > > driver use-cases, increase performance and open up for zero-copy RX. > > Is this based on the page recycle stuff from ixgbe that used to be in > the driver? If so I'd really like to be part of the discussion. Okay, so it is not part of the driver any-longer? I've studied the current ixgbe driver (and other NIC drivers) closely. Do you have some code pointers, to this older code? The likely-fastest recycle code I've see is in the bnx2x driver. If you are interested see: bnx2x_reuse_rx_data(). Again is it a bit open-coded produce/consumer ring queue (which would be nice to also cleanup). To amortize the cost of allocating a single page, most other drivers use the trick of allocating a larger (compound) page, and partition this page into smaller "fragments". Which also amortize the cost of dma_map/unmap (important on non-x86). This is actually problematic performance wise, because packet-data (in these page fragments) only get DMA_sync'ed, and is thus considered "read-only". As netstack need to write packet headers, yet-another (writable) memory area is allocated per packet (plus the SKB meta-data struct). -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href