Hi, Ben Thanks for your reply.
Do you mean that the function poll_timer_wait_until(start + warning_threshold) call only wakeup to do some need log messages and ovsrcu_synchronize() will wait for seq_wait()? According to my understanding, ovsrcu_synchronize() will return until every thread in ovsrcu_threads list have change their seqno to target_seqno. When some thread call ovsrcu_quiesce(), global_seqno is changed. Then seq_wait() will check if global_seqno is changed and call poll_immediate_wake_at() to finish the poll_block()'s waiting. We assume that the first call of seq_wait() in this loop check global_seqno failed for other thread hasn't been ready to call ovsrcu_quiesce(). Then the loop will sleep 1000ms(set by warning_threshold) by poll_block() and check the thread's seqno or global_seqno again when no other threads finish the poll_block()'s waiting in early. If we set warning_threshold to 100ms, the look will check the seqno more frequently and may break earlier. I have test it myself, when warning_threshold is set to 100 as default, the loop 's time indeed reduce to 100ms, that's maybe some evidence. > -----Original Message----- > From: Ben Pfaff [mailto:b...@ovn.org] > Sent: Friday, December 07, 2018 10:37 PM > To: Lilijun (Jerry, Cloud Networking) <jerry.lili...@huawei.com> > Cc: d...@openvswitch.org > Subject: Re: [ovs-dev] [PATCH] [PATCH] rcu: reduce RCU block time > > On Fri, Dec 07, 2018 at 02:03:27PM +0800, Lilijun wrote: > > When calling ovsrcu_synchronize(), it always block 1000ms because we > > poll block until elapsed time become greater than > > warning_threshold(1000).That's too long for some configuration commands. > > So this patch reduces warning_threshold's default value to 100 and > > print logs after it have elapsed more than 1000ms. > > > > Signed-off-by: Lilijun <jerry.lili...@huawei.com> > > This only makes any sense if the seq_wait() doesn't work. Do you have > evidence that is the case? _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev
