Hello Nitin, On Wed, Aug 7, 2019 at 8:13 AM Nitin Katiyar <nitin.kati...@ericsson.com> wrote: > > Each PMD updates the global sequence number for RCU synchronization > purpose with other OVS threads. This is done at every 1025th iteration > in PMD main loop. > > If the PMD thread is responsible for polling large number of queues > that are carrying traffic, it spends a lot of time processing packets > and this results in significant delay in performing the housekeeping > activities. > > If the OVS main thread is waiting to synchronize with the PMD threads > and if those threads delay performing housekeeping activities for > more than 3 sec then LACP processing will be impacted and it will lead > to LACP flaps. Similarly, other controls protocols run by OVS main > thread are impacted. > > For e.g. a PMD thread polling 200 ports/queues with average of 1600 > processing cycles per packet with batch size of 32 may take 10240000 > (200 * 1600 * 32) cycles per iteration. In system with 2.0 GHz CPU > it means more than 5 ms per iteration. So, for 1024 iterations to > complete it would be more than 5 seconds. > > This gets worse when there are PMD threads which are less loaded. > It reduces possibility of getting mutex lock in ovsrcu_try_quiesce() > by heavily loaded PMD and next attempt to quiesce would be after 1024 > iterations. > > With this patch, PMD RCU synchronization will be performed after fixed > interval instead after a fixed number of iterations. This will ensure > that even if the packet processing load is high the RCU synchronization > will not be delayed long. > > Signed-off-by: Anju Thomas <anju.tho...@ericsson.com> > Signed-off-by: Nitin Katiyar <nitin.kati...@ericsson.com> > --- > lib/dpif-netdev-perf.c | 16 ---------------- > lib/dpif-netdev-perf.h | 17 +++++++++++++++++ > lib/dpif-netdev.c | 27 +++++++++++++++++++++++++++ > 3 files changed, 44 insertions(+), 16 deletions(-)
s/To: dev@dpdk.org/To: d...@openvswitch.org/ -- David Marchand
