From mboxrd@z Thu Jan 1 00:00:00 1970 From: Samudrala, Sridhar Date: Wed, 9 Oct 2019 09:19:04 -0700 Subject: [Intel-wired-lan] [PATCH bpf-next 0/4] Enable direct receive on AF_XDP sockets In-Reply-To: <4c316f09-0691-4a1b-f798-73299e978946@intel.com> References: <1570515415-45593-1-git-send-email-sridhar.samudrala@intel.com> <4c316f09-0691-4a1b-f798-73299e978946@intel.com> Message-ID: <411a0287-13fb-672b-740b-10a199e34836@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: intel-wired-lan@osuosl.org List-ID: On 10/8/2019 1:05 AM, Bj?rn T?pel wrote: > On 2019-10-08 08:16, Sridhar Samudrala wrote: >> This is a rework of the following patch series >> https://lore.kernel.org/netdev/1565840783-8269-1-git-send-email-sridhar.samudrala at intel.com/#r >> >> that tried to enable direct receive by bypassing XDP program attached >> to the device. >> >> Based on the community feedback and some suggestions from Bjorn, changed >> the semantics of the implementation to enable direct receive on AF_XDP >> sockets that are bound to a queue only when there is no normal XDP >> program >> attached to the device. >> >> This is accomplished by introducing a special BPF prog pointer >> (DIRECT_XSK) >> that is attached at the time of binding an AF_XDP socket to a queue of a >> device. This is done only if there is no other XDP program attached to >> the device. The normal XDP program has precedence and will replace the >> DIRECT_XSK prog if it is attached later. The main reason to introduce a >> special BPF prog pointer is to minimize the driver changes. The only >> change >> is to use the bpf_get_prog_id() helper when QUERYING the prog id. >> >> Any attach of a normal XDP program will take precedence and the direct >> xsk >> program will be removed. The direct XSK program will be attached >> automatically when the normal XDP program is removed when there are any >> AF_XDP direct sockets associated with that device. >> >> A static key is used to control this feature in order to avoid any >> overhead >> for normal XDP datapath when there are no AF_XDP sockets in direct-xsk >> mode. >> >> Here is some performance data i collected on my Intel Ivybridge based >> development system (Intel(R) Xeon(R) CPU E5-2697 v2 @ 2.70GHz) >> NIC: Intel 40Gb ethernet (i40e) >> >> xdpsock rxdrop 1 core (both app and queue's irq pinned to the same core) >> ??? default : taskset -c 1 ./xdpsock -i enp66s0f0 -r -q 1 >> ??? direct-xsk :taskset -c 1 ./xdpsock -i enp66s0f0 -r -q 1 >> 6.1x improvement in drop rate >> >> xdpsock rxdrop 2 core (app and queue's irq pinned to different cores) >> ??? default : taskset -c 3 ./xdpsock -i enp66s0f0 -r -q 1 >> ??? direct-xsk :taskset -c 3 ./xdpsock -i enp66s0f0 -r -d -q 1 >> 6x improvement in drop rate >> >> xdpsock l2fwd 1 core (both app and queue's irq pinned to the same core) >> ??? default : taskset -c 1 ./xdpsock -i enp66s0f0 -l -q 1 >> ??? direct-xsk :taskset -c 1 ./xdpsock -i enp66s0f0 -l -d -q 1 >> 3.5x improvement in l2fwd rate >> >> xdpsock rxdrop 2 core (app and queue'sirq pinned to different cores) >> ??? default : taskset -c 3 ./xdpsock -i enp66s0f0 -l -q 1 >> ??? direct-xsk :taskset -c 3 ./xdpsock -i enp66s0f0 -l -d -q 1 >> 4.5x improvement in l2fwd rate >> >> dpdk-pktgen is used to send 64byte UDP packets from a link partner and >> ethtool ntuple flow rule is used to redirect packets to queue 1 on the >> system under test. >> > > Thanks for working on this Sridhar! I like this approach! Except from > the bpf_get_prog_id() changes, no driver changes are needed. > > It's also a cleaner (IMO) approach than my previous attempts [1,2,3] > > Would be interesting to see NFP support AF_XDP offloading with this > option. (nudge, nudge). > > A thought: From userland, a direct AF_XDP socket will not appear as an > XDP program is attached to the device (id == 0). Maybe show in ss(8) > (via xsk_diag.c) that the socket is direct? Sure. will add this in the next revision. > > [1] > https://lore.kernel.org/netdev/CAJ+HfNj63QcLY8=y1fF93PZd3XcfiGSrbbWdiGByjTzZQydSSg at mail.gmail.com/ > > [2] > https://lore.kernel.org/netdev/cd952f99-6bad-e0c8-5bcd-f0010218238c at intel.com/ > > [3] > https://lore.kernel.org/netdev/20181207114431.18038-1-bjorn.topel at gmail.com/ >