On Mon, Aug 28, 2023 at 10:27 AM Waiman Long <longman@xxxxxxxxxx> wrote: > > > On 8/28/23 13:07, Yosry Ahmed wrote: > > > >> Here I agree with you. Let's go with the approach which is easy to > >> undo for now. Though I prefer the new explicit interface for flushing, > >> that step would be very hard to undo. Let's reevaluate if the proposed > >> approach shows negative impact on production traffic and I think > >> Cloudflare folks can give us the results soon. > > Do you prefer we also switch to using a mutex (with preemption > > disabled) to avoid the scenario Michal described where flushers give > > up the lock and sleep resulting in an unbounded wait time in the worst > > case? > > Locking with mutex with preemption disabled is an oxymoron. Use spinlock > if you want to have preemption disabled. The purpose of usiing mutex is > to allow the lock owner to sleep, but you can't sleep with preemption > disabled. You need to enable preemption first. You can disable > preemption for a short time in a non-sleeping section of the lock > critical section, but I would not recommend disabling preemption for the > whole critical section. I thought using a mutex with preemption disabled would at least allow waiters to sleep rather than spin, is this not correct (or doesn't matter) ? > > Cheers, > Longman >
