On Thu, Oct 27, 2022, Vipin Sharma wrote: > On Thu, Oct 27, 2022 at 8:56 AM Sean Christopherson <seanjc@xxxxxxxxxx> wrote: > > > > On Thu, Oct 27, 2022, Wang, Wei W wrote: > > > On Wednesday, October 26, 2022 11:44 PM, Sean Christopherson wrote: > > > > If we go this route in the future, we'd need to add a worker trampoline as the > > > > pinning needs to happen in the worker task itself to guarantee that the pinning > > > > takes effect before the worker does anything useful. That should be very > > > > doable. > > > > > > The alternative way is the one I shared before, using this: > > > > > > /* Thread created with attribute ATTR will be limited to run only on > > > the processors represented in CPUSET. */ > > > extern int pthread_attr_setaffinity_np (pthread_attr_t *__attr, > > > size_t __cpusetsize, > > > const cpu_set_t *__cpuset) > > > > > > Basically, the thread is created on the pCPU as user specified. > > > I think this is better than "creating the thread on an arbitrary pCPU > > > and then pinning it to the user specified pCPU in the thread's start routine". > > > > Ah, yeah, that's better. > > > > pthread_create() will internally call sched_setaffinity() syscall > after creation of a thread on a random CPU. So, from the performance > side there is not much difference between the two approaches. > > However, we will still need pin_this_task_to_pcpu()/sched_affinity() > to move the main thread to a specific pCPU, therefore, Heh, that's a good point too. > I am thinking of keeping the current approach unless there is a strong objection > to it. No objection here, I don't see an obvious way to make that helper going away.
