Date: Sun, 20 Mar 2022 05:21:37 UTC
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=262571 --- Comment #6 from commit-hook@FreeBSD.org --- A commit in branch stable/12 references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=fb3644ab2afe777fdd2539bc996a390443f052f1 commit fb3644ab2afe777fdd2539bc996a390443f052f1 Author: Michael Gmelin <grembo@FreeBSD.org> AuthorDate: 2022-03-16 22:08:55 +0000 Commit: Kristof Provost <kp@FreeBSD.org> CommitDate: 2022-03-20 00:24:51 +0000 if_epair: fix race condition on multi-core systems As an unwanted side effect of the performance improvements in 24f0bfbad57b9, epair interfaces stop forwarding traffic on higher load levels when running on multi-core systems. This happens due to a race condition in the logic that decides when to place work in the task queue(s) responsible for processing the content of ring buffers. In order to fix this, a field named state is added to the epair_queue structure. This field is used by the affected functions to signal each other that something happened in the underlying ring buffers that might require work to be scheduled in task queue(s), replacing the existing logic, which relied on checking if ring buffers are empty or not. epair_menq() does: - set BIT_MBUF_QUEUED - queue mbuf - if testandset BIT_QUEUE_TASK: enqueue task epair_tx_start_deferred() does: - swap ring buffers - process mbufs - clear BIT_QUEUE_TASK - if testandclear BIT_MBUF_QUEUED enqueue task PR: 262571 Reported by: Johan Hendriks <firstname.lastname@example.org> MFC after: 3 days Differential Revision: https://reviews.freebsd.org/D34569 (cherry picked from commit 66acf7685bcd8cf23b6c658a991637238a01859e) sys/net/if_epair.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) -- You are receiving this mail because: You are the assignee for the bug.