Re: [PATCH] cpuidle: Allow configuration of the polling interval before cpuidle enters a c-state

2020-11-27 Thread Mel Gorman
On Fri, Nov 27, 2020 at 11:08:11AM -0300, Marcelo Tosatti wrote: > > It requires the admin to know how cpuidle works and why this > > particular polling limit is likely to be suitable for the given > > workload. And whether or not the default polling limit should be > > changed at all. > > KVM

Re: [PATCH] cpuidle: Allow configuration of the polling interval before cpuidle enters a c-state

2020-11-27 Thread Mel Gorman
On Fri, Nov 27, 2020 at 11:08:11AM -0300, Marcelo Tosatti wrote: > > Well, IMV this is not straightforward at all. > > > > It requires the admin to know how cpuidle works and why this > > particular polling limit is likely to be suitable for the given > > workload. And whether or not the default

Re: [PATCH] cpuidle: Allow configuration of the polling interval before cpuidle enters a c-state

2020-11-27 Thread Marcelo Tosatti
On Thu, Nov 26, 2020 at 07:24:41PM +0100, Rafael J. Wysocki wrote: > On Thu, Nov 26, 2020 at 6:25 PM Mel Gorman > wrote: > > > > It was noted that a few workloads that idle rapidly regressed when commit > > 36fcb4292473 ("cpuidle: use first valid target residency as poll time") > > was merged.

Re: [PATCH] cpuidle: Allow configuration of the polling interval before cpuidle enters a c-state

2020-11-27 Thread Mel Gorman
On Thu, Nov 26, 2020 at 08:31:51PM +, Mel Gorman wrote: > > > and it is reasonable behaviour but it should be tunable. > > > > Only if there is no way to cover all of the relevant use cases in a > > generally acceptable way without adding more module params etc. > > > > In this particular

Re: [PATCH] cpuidle: Allow configuration of the polling interval before cpuidle enters a c-state

2020-11-26 Thread Mel Gorman
On Thu, Nov 26, 2020 at 07:24:41PM +0100, Rafael J. Wysocki wrote: > On Thu, Nov 26, 2020 at 6:25 PM Mel Gorman > wrote: > > It was noted that a few workloads that idle rapidly regressed when commit > > 36fcb4292473 ("cpuidle: use first valid target residency as poll time") > > was merged. The

Re: [PATCH] cpuidle: Allow configuration of the polling interval before cpuidle enters a c-state

2020-11-26 Thread Rafael J. Wysocki
On Thu, Nov 26, 2020 at 6:25 PM Mel Gorman wrote: > > It was noted that a few workloads that idle rapidly regressed when commit > 36fcb4292473 ("cpuidle: use first valid target residency as poll time") > was merged. The workloads in question were heavy communicators that idle > rapidly and were

[PATCH] cpuidle: Allow configuration of the polling interval before cpuidle enters a c-state

2020-11-26 Thread Mel Gorman
It was noted that a few workloads that idle rapidly regressed when commit 36fcb4292473 ("cpuidle: use first valid target residency as poll time") was merged. The workloads in question were heavy communicators that idle rapidly and were impacted by the c-state exit latency as the active CPUs were