Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1724812

Re: [RFC PATCH v2 0/7] x86/idle: add halt poll support

Show all headers | View raw

2017-09-01 14:32 GMT+08:00 Yang Zhang <yang.zhang.wz@gmail.com>:
> On 2017/8/29 22:02, Wanpeng Li wrote:
>>>
>>> Here is the data we get when running benchmark netperf:
>>>
>>>     2. w/ patch:
>>>        halt_poll_threshold=10000 -- 15803.89 bits/s -- 159.5 %CPU
>>>        halt_poll_threshold=20000 -- 15899.04 bits/s -- 161.5 %CPU
>>>        halt_poll_threshold=30000 -- 15642.38 bits/s -- 161.8 %CPU
>>>        halt_poll_threshold=40000 -- 18040.76 bits/s -- 184.0 %CPU
>>>        halt_poll_threshold=50000 -- 18877.61 bits/s -- 197.3 %CPU
>>>
>>>     3. kvm dynamic poll
>>>        halt_poll_ns=10000 -- 15876.00 bits/s -- 172.2 %CPU
>>>        halt_poll_ns=20000 -- 15602.58 bits/s -- 185.4 %CPU
>>>        halt_poll_ns=30000 -- 15930.69 bits/s -- 194.4 %CPU
>>>        halt_poll_ns=40000 -- 16413.09 bits/s -- 195.3 %CPU
>>>        halt_poll_ns=50000 -- 16417.42 bits/s -- 196.3 %CPU
>>>
>>
>> Actually I'm not sure how much sense it makes to introduce this pv
>> stuff and the duplicate adaptive halt-polling logic as what has
>> already been done in kvm w/o obvious benefit for real workload like >
>> netperf. In addition, as you mentioned offline to me, enable both the
>> patchset and the adaptive halt-polling logic in kvm simultaneously can
>> result in more cpu power consumption. I remembered that David from
>
>
> If we use poll in KVM side, it will consume more cpu than in guest side. If
> use both two, then we can get the same performance as only enable guest side
> poll but it will cost more cpu because of poll KVM side. It means we should
> disable KVM side poll since it cannot give much improvement than  guest side
> except consume more cpu and large latency.

How can message passing workloads in windows guest survive?

Regards,
Wanpeng Li

>
>> Google mentioned that Windows Event Objects can get 2x latency
>> improvement in KVM FORUM, which means that the adaptive halt-polling
>> in kvm should be enabled by default. So if the windows guests and
>> linux guests are mixed on the same host, then this patchset will
>> result in more cpu power consumption if the customer enable the
>> polling in the linux guest. Anyway, if the patchset is finally
>> acceptable by maintainer, I will introduce the generic adaptive
>> halt-polling framework in kvm to avoid the duplicate logic.
>
>
> We will add more conditions than the current algorithm in future. But it's
> ok to use the one copy currently, we will do it in next version.
>
>
>
> --
> Yang
> Alibaba Cloud Computing

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

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

csiph-web