On 15/07/2021 23:57, Pravin Shelar wrote: > On Thu, Jul 15, 2021 at 5:28 AM Mark Gray <mark.d.g...@redhat.com> wrote: >> >> The Open vSwitch kernel module uses the upcall mechanism to send >> packets from kernel space to user space when it misses in the kernel >> space flow table. The upcall sends packets via a Netlink socket. >> Currently, a Netlink socket is created for every vport. In this way, >> there is a 1:1 mapping between a vport and a Netlink socket. >> When a packet is received by a vport, if it needs to be sent to >> user space, it is sent via the corresponding Netlink socket. >> >> This mechanism, with various iterations of the corresponding user >> space code, has seen some limitations and issues: >> >> * On systems with a large number of vports, there is a correspondingly >> large number of Netlink sockets which can limit scaling. >> (https://bugzilla.redhat.com/show_bug.cgi?id=1526306) >> * Packet reordering on upcalls. >> (https://bugzilla.redhat.com/show_bug.cgi?id=1844576) >> * A thundering herd issue. >> (https://bugzilla.redhat.com/show_bug.cgi?id=1834444) >> >> This patch introduces an alternative, feature-negotiated, upcall >> mode using a per-cpu dispatch rather than a per-vport dispatch. >> >> In this mode, the Netlink socket to be used for the upcall is >> selected based on the CPU of the thread that is executing the upcall. >> In this way, it resolves the issues above as: >> >> a) The number of Netlink sockets scales with the number of CPUs >> rather than the number of vports. >> b) Ordering per-flow is maintained as packets are distributed to >> CPUs based on mechanisms such as RSS and flows are distributed >> to a single user space thread. >> c) Packets from a flow can only wake up one user space thread. >> >> The corresponding user space code can be found at: >> https://mail.openvswitch.org/pipermail/ovs-dev/2021-July/385139.html >> >> Bugzilla: https://bugzilla.redhat.com/1844576 >> Signed-off-by: Mark Gray <mark.d.g...@redhat.com> >> Acked-by: Flavio Leitner <f...@sysclose.org> > > Acked-by: Pravin B Shelar <pshe...@ovn.org> > > Thanks, >
Thanks for the review Pravin. _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev
