On Fri, 21 Jul 2023, Chuck Lever III wrote: > > > On Jul 19, 2023, at 7:44 PM, Chuck Lever III <chuck.lever@xxxxxxxxxx> wrote: > > > > > > > >> On Jul 19, 2023, at 7:20 PM, NeilBrown <neilb@xxxxxxx> wrote: > >> > >> On Wed, 19 Jul 2023, Chuck Lever III wrote: > >>> > >>>> On Jul 18, 2023, at 9:16 PM, NeilBrown <neilb@xxxxxxx> wrote: > >>>> > >>>> On Tue, 18 Jul 2023, Chuck Lever wrote: > >>>>> On Tue, Jul 18, 2023 at 04:38:08PM +1000, NeilBrown wrote: > >>>>>> No callers of svc_pool_wake_idle_thread() care which thread was woken - > >>>>>> except one that wants to trace the wakeup. For now we drop that > >>>>>> tracepoint. > >>>>> > >>>>> That's an important tracepoint, IMO. > >>>>> > >>>>> It might be better to have svc_pool_wake_idle_thread() return void > >>>>> right from it's introduction, and move the tracepoint into that > >>>>> function. I can do that and respin if you agree. > >>>> > >>>> Mostly I agree. > >>>> > >>>> It isn't clear to me how you would handle trace_svc_xprt_enqueue(), > >>>> as there would be no code that can see both the trigger xprt, and the > >>>> woken rqst. > >>>> > >>>> I also wonder if having the trace point when the wake-up is requested > >>>> makes any sense, as there is no guarantee that thread with handle that > >>>> xprt. > >>>> > >>>> Maybe the trace point should report when the xprt is dequeued. i.e. > >>>> maybe trace_svc_pool_awoken() should report the pid, and we could have > >>>> trace_svc_xprt_enqueue() only report the xprt, not the rqst. > >>> > >>> I'll come up with something that rearranges the tracepoints so that > >>> svc_pool_wake_idle_thread() can return void. > >> > >> My current draft code has svc_pool_wake_idle_thread() returning bool - > >> if it found something to wake up - purely for logging. > > > > This is also where I have ended up. I'll post an update probably tomorrow > > my time. Too much other stuff going on to finish it today. > > Pushed to https://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git > in branch topic-sunrpc-thread-scheduling Another thing. You have made svc_pool_wake_idle_thread() return, but for different reasons than me. I wanted bool so I could trace a wake up due to enqueuing an xprt differently from a wakeup due to a call to svc_wake_up(). I thought the difference might be important. You have it returning a bool so that: - in one case you can set SP_CONGESTED - but that can be safely set inside svc_pool_wake_idle_thread() - in another case so SP_TASK_PENDING can be set. But I think it is best to set that anyway, and clear it when svc_recv() wakes up. So maybe it can return void after all. Thanks, NeilBrown
