Re: [Xen-devel] [PATCH v3 5/6] xen: RCU: avoid busy waiting until the end of grace period.

2017-09-06 Thread Jan Beulich
>>> On 05.09.17 at 19:13, wrote: > On Wed, 2017-08-30 at 01:18 -0600, Jan Beulich wrote: >> > > > On 29.08.17 at 18:06, wrote: >> > Dario is on holiday, and I think it would be good to get this >> > functionality in sooner rather than later to

Re: [Xen-devel] [PATCH v3 5/6] xen: RCU: avoid busy waiting until the end of grace period.

2017-09-05 Thread Dario Faggioli
On Wed, 2017-08-30 at 01:18 -0600, Jan Beulich wrote: > > > > On 29.08.17 at 18:06, wrote: > > > > On 08/22/2017 02:04 PM, Jan Beulich wrote: > > > > > > On 18.08.17 at 20:04, wrote: > > > > > > > > --- a/xen/arch/x86/cpu/mwait-idle.c > > >

Re: [Xen-devel] [PATCH v3 5/6] xen: RCU: avoid busy waiting until the end of grace period.

2017-08-30 Thread George Dunlap
On Wed, Aug 30, 2017 at 8:18 AM, Jan Beulich wrote: >> Apart from this, are you OK with the patch? > > Yes. > >> Dario is on holiday, and I think it would be good to get this >> functionality in sooner rather than later to shake out as many bugs as >> possible. Would you be

Re: [Xen-devel] [PATCH v3 5/6] xen: RCU: avoid busy waiting until the end of grace period.

2017-08-30 Thread Jan Beulich
>>> On 29.08.17 at 18:06, wrote: > On 08/22/2017 02:04 PM, Jan Beulich wrote: > On 18.08.17 at 20:04, wrote: >>> --- a/xen/arch/x86/cpu/mwait-idle.c >>> +++ b/xen/arch/x86/cpu/mwait-idle.c >>> @@ -741,9 +741,8 @@ static void

Re: [Xen-devel] [PATCH v3 5/6] xen: RCU: avoid busy waiting until the end of grace period.

2017-08-29 Thread George Dunlap
On 08/22/2017 02:04 PM, Jan Beulich wrote: On 18.08.17 at 20:04, wrote: >> --- a/xen/arch/x86/cpu/mwait-idle.c >> +++ b/xen/arch/x86/cpu/mwait-idle.c >> @@ -741,9 +741,8 @@ static void mwait_idle(void) >> } >> >> cpufreq_dbs_timer_suspend(); >> - >>

Re: [Xen-devel] [PATCH v3 5/6] xen: RCU: avoid busy waiting until the end of grace period.

2017-08-29 Thread George Dunlap
On 08/18/2017 07:04 PM, Dario Faggioli wrote: > On the CPU where a callback is queued, cpu_is_haltable() > returns false (due to rcu_needs_cpu() being itself false). > That means the CPU would spin inside idle_loop(), continuously > calling do_softirq(), and, in there, continuously checking >

Re: [Xen-devel] [PATCH v3 5/6] xen: RCU: avoid busy waiting until the end of grace period.

2017-08-22 Thread Jan Beulich
>>> On 18.08.17 at 20:04, wrote: > --- a/xen/arch/x86/cpu/mwait-idle.c > +++ b/xen/arch/x86/cpu/mwait-idle.c > @@ -741,9 +741,8 @@ static void mwait_idle(void) > } > > cpufreq_dbs_timer_suspend(); > - > sched_tick_suspend(); > - /*

[Xen-devel] [PATCH v3 5/6] xen: RCU: avoid busy waiting until the end of grace period.

2017-08-18 Thread Dario Faggioli
On the CPU where a callback is queued, cpu_is_haltable() returns false (due to rcu_needs_cpu() being itself false). That means the CPU would spin inside idle_loop(), continuously calling do_softirq(), and, in there, continuously checking rcu_pending(), in a tight loop. Let's instead allow the CPU