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Re: [RFC PATCH v2 3/7] sched/idle: Add poll before enter real idle path

From Quan Xu <quan.xu0@gmail.com>
Newsgroups linux.kernel
Subject Re: [RFC PATCH v2 3/7] sched/idle: Add poll before enter real idle path
Date 2017-09-01 09:00 +0200
Message-ID <ukO5Q-dZ-27@gated-at.bofh.it> (permalink)
References <ujNbP-25K-5@gated-at.bofh.it> <ujNbP-25K-9@gated-at.bofh.it> <ujPQm-3Mg-9@gated-at.bofh.it>
Organization linux.* mail to news gateway

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on 2017/8/29 22:39, Borislav Petkov wrote:
> On Tue, Aug 29, 2017 at 11:46:37AM +0000, Yang Zhang wrote:
>> Add poll in do_idle. For UP VM, if there are running task, it will not
>> goes into idle path, so we only enable poll in SMP VM.
>>
>> Signed-off-by: Yang Zhang <yang.zhang.wz@gmail.com>
>> Signed-off-by: Quan Xu <quan.xu0@gmail.com>
>> Cc: Thomas Gleixner <tglx@linutronix.de>
>> Cc: Ingo Molnar <mingo@redhat.com>
>> Cc: "H. Peter Anvin" <hpa@zytor.com>
>> Cc: x86@kernel.org
>> Cc: Peter Zijlstra <peterz@infradead.org>
>> Cc: Borislav Petkov <bp@alien8.de>
>> Cc: Kyle Huey <me@kylehuey.com>
>> Cc: Andy Lutomirski <luto@kernel.org>
>> Cc: Len Brown <len.brown@intel.com>
>> Cc: linux-kernel@vger.kernel.org
>> ---
>>   arch/x86/kernel/process.c | 7 +++++++
>>   kernel/sched/idle.c       | 2 ++
>>   2 files changed, 9 insertions(+)
>>
>> diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
>> index 3ca1980..def4113 100644
>> --- a/arch/x86/kernel/process.c
>> +++ b/arch/x86/kernel/process.c
>> @@ -332,6 +332,13 @@ void arch_cpu_idle(void)
>>   	x86_idle();
>>   }
>>   
>> +#if defined(CONFIG_SMP) && defined(CONFIG_PARAVIRT)
>> +void arch_cpu_idle_poll(void)
>> +{
>> +	paravirt_idle_poll();
>> +}
>> +#endif
> So this will get called on any system which has CONFIG_PARAVIRT enabled
> *even* if they're not running any guests.
>
> Huh?
    Borislav ,
    yes,  this will get called on any system which has CONFIG_PARAVIRT 
enabled.

    but if they are not running any guests,  the callback is 
paravirt_nop() ,
    IIUC which is as similar as the other paravirt_*, such as 
paravirt_pgd_free()..

  - Quan

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Thread

[RFC PATCH v2 0/7] x86/idle: add halt poll support Yang Zhang <yang.zhang.wz@gmail.com> - 2017-08-29 13:50 +0200
  [RFC PATCH v2 3/7] sched/idle: Add poll before enter real idle path Yang Zhang <yang.zhang.wz@gmail.com> - 2017-08-29 13:50 +0200
    Re: [RFC PATCH v2 3/7] sched/idle: Add poll before enter real idle  path Peter Zijlstra <peterz@infradead.org> - 2017-08-29 14:50 +0200
      Re: [RFC PATCH v2 3/7] sched/idle: Add poll before enter real idle  path Quan Xu <quan.xu0@gmail.com> - 2017-09-01 08:00 +0200
    Re: [RFC PATCH v2 3/7] sched/idle: Add poll before enter real idle  path Borislav Petkov <bp@alien8.de> - 2017-08-29 16:40 +0200
      Re: [RFC PATCH v2 3/7] sched/idle: Add poll before enter real idle  path Quan Xu <quan.xu0@gmail.com> - 2017-09-01 09:00 +0200
  [RFC PATCH v2 1/7] x86/paravirt: Add pv_idle_ops to paravirt ops Yang Zhang <yang.zhang.wz@gmail.com> - 2017-08-29 13:50 +0200
    Re: [RFC PATCH v2 1/7] x86/paravirt: Add pv_idle_ops to paravirt ops Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> - 2017-08-29 16:10 +0200
      Re: [RFC PATCH v2 1/7] x86/paravirt: Add pv_idle_ops to paravirt ops Juergen Gross <jgross@suse.com> - 2017-08-30 09:40 +0200
      Re: [RFC PATCH v2 1/7] x86/paravirt: Add pv_idle_ops to paravirt ops Yang Zhang <yang.zhang.wz@gmail.com> - 2017-09-01 09:00 +0200
  [RFC PATCH v2 5/7] Documentation: Add three sysctls for smart idle poll Yang Zhang <yang.zhang.wz@gmail.com> - 2017-08-29 13:50 +0200
    Re: [RFC PATCH v2 5/7] Documentation: Add three sysctls for smart  idle poll "Luis R. Rodriguez" <mcgrof@kernel.org> - 2017-08-29 19:30 +0200
  [RFC PATCH v2 2/7] KVM guest: register kvm_idle_poll for pv_idle_ops Yang Zhang <yang.zhang.wz@gmail.com> - 2017-08-29 13:50 +0200
  [RFC PATCH v2 4/7] x86/paravirt: Add update in x86/paravirt pv_idle_ops Yang Zhang <yang.zhang.wz@gmail.com> - 2017-08-29 13:50 +0200
  [RFC PATCH v2 7/7] sched/idle: update poll time when wakeup from idle Yang Zhang <yang.zhang.wz@gmail.com> - 2017-08-29 13:50 +0200
    Re: [RFC PATCH v2 7/7] sched/idle: update poll time when wakeup from  idle Peter Zijlstra <peterz@infradead.org> - 2017-08-29 14:50 +0200
      Re: [RFC PATCH v2 7/7] sched/idle: update poll time when wakeup from  idle Yang Zhang <yang.zhang.wz@gmail.com> - 2017-09-01 09:40 +0200
  Re: [RFC PATCH v2 0/7] x86/idle: add halt poll support Alexander Graf <agraf@suse.de> - 2017-08-29 14:00 +0200
    Re: [RFC PATCH v2 0/7] x86/idle: add halt poll support Yang Zhang <yang.zhang.wz@gmail.com> - 2017-09-01 08:30 +0200
  Re: [RFC PATCH v2 0/7] x86/idle: add halt poll support Andi Kleen <andi@firstfloor.org> - 2017-08-29 15:10 +0200
  Re: [RFC PATCH v2 0/7] x86/idle: add halt poll support Wanpeng Li <kernellwp@gmail.com> - 2017-08-29 16:10 +0200
    Re: [RFC PATCH v2 0/7] x86/idle: add halt poll support Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> - 2017-08-29 16:30 +0200
    Re: [RFC PATCH v2 0/7] x86/idle: add halt poll support "Michael S. Tsirkin" <mst@redhat.com> - 2017-08-29 16:40 +0200
    Re: [RFC PATCH v2 0/7] x86/idle: add halt poll support Yang Zhang <yang.zhang.wz@gmail.com> - 2017-09-01 08:40 +0200
      Re: [RFC PATCH v2 0/7] x86/idle: add halt poll support Wanpeng Li <kernellwp@gmail.com> - 2017-09-01 09:00 +0200
    Re: [RFC PATCH v2 0/7] x86/idle: add halt poll support Yang Zhang <yang.zhang.wz@gmail.com> - 2017-09-01 08:50 +0200
      Re: [RFC PATCH v2 0/7] x86/idle: add halt poll support Wanpeng Li <kernellwp@gmail.com> - 2017-09-01 09:00 +0200
        Re: [RFC PATCH v2 0/7] x86/idle: add halt poll support Yang Zhang <yang.zhang.wz@gmail.com> - 2017-09-01 10:00 +0200
  Re: [RFC PATCH v2 0/7] x86/idle: add halt poll support "Michael S. Tsirkin" <mst@redhat.com> - 2017-08-29 17:00 +0200

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