Re: [PATCH v4 1/5] sched/deadline: Refer to cpudl.elements atomically

2017-05-22 Thread Byungchul Park
On Tue, May 16, 2017 at 09:10:53AM -0400, Steven Rostedt wrote: > On Tue, 16 May 2017 11:32:41 +0100 > Juri Lelli wrote: > > > > Not sure, but if we are going to retry a lot it might be better off to > > put proper locking instead? We could also simply bail out when we notice > > Actually, lock

Re: [PATCH v4 1/5] sched/deadline: Refer to cpudl.elements atomically

2017-05-16 Thread Steven Rostedt
On Tue, 16 May 2017 11:32:41 +0100 Juri Lelli wrote: > Not sure, but if we are going to retry a lot it might be better off to > put proper locking instead? We could also simply bail out when we notice Actually, locking can make it much worse. I've been playing with RT on boxes with 240 cores (w

Re: [PATCH v4 1/5] sched/deadline: Refer to cpudl.elements atomically

2017-05-16 Thread Juri Lelli
On 16/05/17 15:52, Byungchul Park wrote: > On Fri, May 12, 2017 at 10:25:30AM -0400, Steven Rostedt wrote: > > On Fri, 12 May 2017 14:48:45 +0900 > > Byungchul Park wrote: > > > > > cpudl.elements is an instance that should be protected with a spin lock. > > > Without it, the code would be insane

Re: [PATCH v4 1/5] sched/deadline: Refer to cpudl.elements atomically

2017-05-16 Thread Byungchul Park
On Mon, May 15, 2017 at 09:36:29AM +0100, Juri Lelli wrote: > Hi, > > On 12/05/17 10:25, Steven Rostedt wrote: > > On Fri, 12 May 2017 14:48:45 +0900 > > Byungchul Park wrote: > > > > > cpudl.elements is an instance that should be protected with a spin lock. > > > Without it, the code would be i

Re: [PATCH v4 1/5] sched/deadline: Refer to cpudl.elements atomically

2017-05-15 Thread Byungchul Park
On Fri, May 12, 2017 at 10:25:30AM -0400, Steven Rostedt wrote: > On Fri, 12 May 2017 14:48:45 +0900 > Byungchul Park wrote: > > > cpudl.elements is an instance that should be protected with a spin lock. > > Without it, the code would be insane. > > And how much contention will this add? Spin lo

Re: [PATCH v4 1/5] sched/deadline: Refer to cpudl.elements atomically

2017-05-15 Thread Juri Lelli
Hi, On 12/05/17 10:25, Steven Rostedt wrote: > On Fri, 12 May 2017 14:48:45 +0900 > Byungchul Park wrote: > > > cpudl.elements is an instance that should be protected with a spin lock. > > Without it, the code would be insane. > > And how much contention will this add? Spin locks in the schedul

Re: [PATCH v4 1/5] sched/deadline: Refer to cpudl.elements atomically

2017-05-12 Thread Steven Rostedt
On Fri, 12 May 2017 14:48:45 +0900 Byungchul Park wrote: > cpudl.elements is an instance that should be protected with a spin lock. > Without it, the code would be insane. And how much contention will this add? Spin locks in the scheduler code that are shared among a domain can cause huge latenc