Messages in this thread | | | Date | Fri, 9 Jun 2023 10:54:04 -0300 | From | Marcelo Tosatti <> | Subject | Re: [PATCH] sched/idle: disable tick in idle=poll idle entry |
| |
On Thu, Jun 08, 2023 at 10:34:00AM +0200, Peter Zijlstra wrote: > On Wed, Jun 07, 2023 at 10:10:46PM -0300, Marcelo Tosatti wrote: > > > > Commit a5183862e76fdc25f36b39c2489b816a5c66e2e5 > > ("tick/nohz: Conditionally restart tick on idle exit") allows > > a nohz_full CPU to enter idle and return from it with the > > scheduler tick disabled (since the tick might be undesired noise). > > > > The idle=poll case still unconditionally restarts the tick when entering > > idle. > > > > To reduce the noise for that case as well, stop the tick when entering > > idle, for the idle=poll case. > > > > tick_nohz_idle_exit (called if the NEED_RESCHED bit is set) > > is responsible for re-enabling the tick when necessary. > > Who cares and why?
Systems that use isolcpus/nohz_full, and use idle=poll to avoid sleeping. For example:
https://github.com/intel/FlexRAN/blob/master/README.md
More specifically, the case which HLTs (via nanosleep usually) is:
https://www.isa.org/intech-home/2022/february-2022/departments/what-you-may-not-know-about-softplcs
Can add this to the next version of the patch (unless you have any other comments).
Thanks.
| |