On Wed, Aug 21, 2019 at 08:20:48AM +0000, Long Li wrote: > >>>Subject: Re: [PATCH 1/3] sched: define a function to report the number of > >>>context switches on a CPU > >>> > >>>On Mon, Aug 19, 2019 at 11:14:27PM -0700, lon...@linuxonhyperv.com > >>>wrote: > >>>> From: Long Li <lon...@microsoft.com> > >>>> > >>>> The number of context switches on a CPU is useful to determine how > >>>> busy this CPU is on processing IRQs. Export this information so it can > >>>> be used by device drivers. > >>> > >>>Please do explain that; because I'm not seeing how number of switches > >>>relates to processing IRQs _at_all_! > > Some kernel components rely on context switch to progress, for example > watchdog and RCU. On a CPU with reasonable interrupt load, it > continues to make context switches, normally a number of switches per > seconds.
That isn't true; RCU is perfectly fine with a single task always running and not making context switches, and so is the watchdog.
