On Sunday, October 14, 2018 8:41 PM, Wei Wang wrote:
> Here is the plan I have in mind:
> #1 Creates a host perf event on the guest's first bit-setting to
> MSR_CORE_PERF_GLOBAL_CTRL; Meanwhile, disable the intercept of guest
> access to this perf counter related MSRs (i.e. config_base and
On Sunday, October 14, 2018 8:41 PM, Wei Wang wrote:
> Here is the plan I have in mind:
> #1 Creates a host perf event on the guest's first bit-setting to
> MSR_CORE_PERF_GLOBAL_CTRL; Meanwhile, disable the intercept of guest
> access to this perf counter related MSRs (i.e. config_base and
On 10/13/2018 09:30 PM, Peter Zijlstra wrote:
On Fri, Oct 12, 2018 at 08:20:17PM +0800, Wei Wang wrote:
Guest changing MSR_CORE_PERF_GLOBAL_CTRL causes KVM to reprogram pmc
counters, which re-allocates a host perf event. This process is
Yea gawds, that's horrific. Why does it do that? We have
On 10/13/2018 09:30 PM, Peter Zijlstra wrote:
On Fri, Oct 12, 2018 at 08:20:17PM +0800, Wei Wang wrote:
Guest changing MSR_CORE_PERF_GLOBAL_CTRL causes KVM to reprogram pmc
counters, which re-allocates a host perf event. This process is
Yea gawds, that's horrific. Why does it do that? We have
On 10/13/2018 04:09 PM, Paolo Bonzini wrote:
It's not clear to me why you're special casing PMIs here. The optimization
should work generically, right?
Yeah, you can even just check if the counter is in the struct
cpu_hw_events guest mask, and if so always write the counter MSR directly.
On 10/13/2018 04:09 PM, Paolo Bonzini wrote:
It's not clear to me why you're special casing PMIs here. The optimization
should work generically, right?
Yeah, you can even just check if the counter is in the struct
cpu_hw_events guest mask, and if so always write the counter MSR directly.
On Fri, Oct 12, 2018 at 08:20:17PM +0800, Wei Wang wrote:
> Guest changing MSR_CORE_PERF_GLOBAL_CTRL causes KVM to reprogram pmc
> counters, which re-allocates a host perf event. This process is
Yea gawds, that's horrific. Why does it do that? We have
PERF_EVENT_IOC_PERIOD which does that much
On Fri, Oct 12, 2018 at 08:20:17PM +0800, Wei Wang wrote:
> Guest changing MSR_CORE_PERF_GLOBAL_CTRL causes KVM to reprogram pmc
> counters, which re-allocates a host perf event. This process is
Yea gawds, that's horrific. Why does it do that? We have
PERF_EVENT_IOC_PERIOD which does that much
On 12/10/2018 18:30, Andi Kleen wrote:
>> 4. Results
>> - Without this optimization, the guest pmi handling time is
>> ~450 ns, and the max sampling rate is reduced to 250.
>> - With this optimization, the guest pmi handling time is ~9000 ns
>> (i.e. 1 / 500 of the
On 12/10/2018 18:30, Andi Kleen wrote:
>> 4. Results
>> - Without this optimization, the guest pmi handling time is
>> ~450 ns, and the max sampling rate is reduced to 250.
>> - With this optimization, the guest pmi handling time is ~9000 ns
>> (i.e. 1 / 500 of the
On Saturday, October 13, 2018 12:31 AM, Andi Kleen wrote:
> > 4. Results
> > - Without this optimization, the guest pmi handling time is
> > ~450 ns, and the max sampling rate is reduced to 250.
> > - With this optimization, the guest pmi handling time is ~9000 ns
> > (i.e.
On Saturday, October 13, 2018 12:31 AM, Andi Kleen wrote:
> > 4. Results
> > - Without this optimization, the guest pmi handling time is
> > ~450 ns, and the max sampling rate is reduced to 250.
> > - With this optimization, the guest pmi handling time is ~9000 ns
> > (i.e.
Hi,
On 12.10.2018 19:30, Andi Kleen wrote:
>> 4. Results
>> - Without this optimization, the guest pmi handling time is
>> ~450 ns, and the max sampling rate is reduced to 250.
>> - With this optimization, the guest pmi handling time is ~9000 ns
>> (i.e. 1 / 500 of the
Hi,
On 12.10.2018 19:30, Andi Kleen wrote:
>> 4. Results
>> - Without this optimization, the guest pmi handling time is
>> ~450 ns, and the max sampling rate is reduced to 250.
>> - With this optimization, the guest pmi handling time is ~9000 ns
>> (i.e. 1 / 500 of the
> 4. Results
> - Without this optimization, the guest pmi handling time is
> ~450 ns, and the max sampling rate is reduced to 250.
> - With this optimization, the guest pmi handling time is ~9000 ns
> (i.e. 1 / 500 of the non-optimization case), and the max sampling
>
> 4. Results
> - Without this optimization, the guest pmi handling time is
> ~450 ns, and the max sampling rate is reduced to 250.
> - With this optimization, the guest pmi handling time is ~9000 ns
> (i.e. 1 / 500 of the non-optimization case), and the max sampling
>
Guest changing MSR_CORE_PERF_GLOBAL_CTRL causes KVM to reprogram pmc
counters, which re-allocates a host perf event. This process is
heavyweight and results in a long guest pmi handling time. This also
makes the perf samping events in the guest hard to move forward as the
sampling rate will be
Guest changing MSR_CORE_PERF_GLOBAL_CTRL causes KVM to reprogram pmc
counters, which re-allocates a host perf event. This process is
heavyweight and results in a long guest pmi handling time. This also
makes the perf samping events in the guest hard to move forward as the
sampling rate will be
18 matches
Mail list logo