Re: [PATCH 1/3] sched: better handling for busy polling loops

2020-10-28 Thread Josh Don
On Fri, Oct 23, 2020 at 10:49 AM Jakub Kicinski wrote: > > On Thu, 22 Oct 2020 20:29:42 -0700 Josh Don wrote: > > Busy polling loops in the kernel such as network socket poll and kvm > > halt polling have performance problems related to process scheduler load > > accounting. > > > > Both of the bu

Re: [PATCH 1/3] sched: better handling for busy polling loops

2020-10-27 Thread Josh Don
On Fri, Oct 23, 2020 at 12:19 AM Peter Zijlstra wrote: > > On Thu, Oct 22, 2020 at 08:29:42PM -0700, Josh Don wrote: > > Busy polling loops in the kernel such as network socket poll and kvm > > halt polling have performance problems related to process scheduler load > > accounting. > > AFAICT you'

Re: [PATCH 1/3] sched: better handling for busy polling loops

2020-10-23 Thread Jakub Kicinski
On Thu, 22 Oct 2020 20:29:42 -0700 Josh Don wrote: > Busy polling loops in the kernel such as network socket poll and kvm > halt polling have performance problems related to process scheduler load > accounting. > > Both of the busy polling examples are opportunistic - they relinquish > the cpu if

Re: [PATCH 1/3] sched: better handling for busy polling loops

2020-10-23 Thread Paolo Bonzini
On 23/10/20 09:19, Peter Zijlstra wrote: >> +/* >> + * preemption needs to be kept disabled between prepare_to_busy_poll() >> + * and end_busy_poll(). >> + */ >> +BUG_ON(preemptible()); >> +if (allow_resched) >> +preempt_enable(); >> +else >> +pre

Re: [PATCH 1/3] sched: better handling for busy polling loops

2020-10-23 Thread Vincent Guittot
On Fri, 23 Oct 2020 at 05:30, Josh Don wrote: > > Busy polling loops in the kernel such as network socket poll and kvm > halt polling have performance problems related to process scheduler load > accounting. > > Both of the busy polling examples are opportunistic - they relinquish > the cpu if ano

Re: [PATCH 1/3] sched: better handling for busy polling loops

2020-10-23 Thread Peter Zijlstra
On Thu, Oct 22, 2020 at 08:29:42PM -0700, Josh Don wrote: > Busy polling loops in the kernel such as network socket poll and kvm > halt polling have performance problems related to process scheduler load > accounting. AFAICT you're not actually fixing the load accounting issue at all. > This chan