So, how do we address the performance regression fixed by this patch?
Olaf
Am Mon, 12 Mar 2018 10:15:08 +0100
schrieb Olaf Hering :
> Am Tue, 6 Mar 2018 11:07:54 +
> schrieb Andrew Cooper :
>
> > > Add a new domctl XEN_DOMCTL_set_vtsc_tolerance_khz to adjust the
> > > tolerance value of a r
Am Tue, 6 Mar 2018 11:07:54 +
schrieb Andrew Cooper :
> > Add a new domctl XEN_DOMCTL_set_vtsc_tolerance_khz to adjust the
> > tolerance value of a running domU that is supposed to be migrated.
> Please can we not proliferate the domctls.
> This looks like it should be part of the set_tsc_in
>>> On 06.03.18 at 12:07, wrote:
> On 06/03/18 10:41, Olaf Hering wrote:
>> With this option the host admin can decide how a domU should behave when
>> it is migrated across systems of the same class. Since there is always
>> some jitter when Xen calibrates the cpu_khz value, all hosts of the same
Am Tue, 6 Mar 2018 11:07:54 +
schrieb Andrew Cooper :
> We should see about using better sources of information. For one, many
> Intel systems actually expose the TSC frequency in the bottom of the
> PLATFORM_INFO MSR, although this isn't architectural, and has been
> replaced with CPUID info
Am Tue, 6 Mar 2018 11:07:54 +
schrieb Andrew Cooper :
> > One option to avoid the TSC option is to run domUs with tsc_mode=native.
> > This has the drawback that migrating a domU from a "2.3GHz" class host
> > to a "2.4GHz" class host may change the rate at wich the TSC counter
> > increases,
Am Tue, 6 Mar 2018 11:07:54 +
schrieb Andrew Cooper :
> This looks like it should be part of the set_tsc_info hypercall, not a
> separate hypercall.
How would one adjust the value at runtime with set_tsc_info of a running domU?
It seems to me set_tsc_info does way more than just applying some
On 06/03/18 10:41, Olaf Hering wrote:
> Add an option to control when vTSC emulation will be activated for a
> domU with tsc_mode=default. Without such option each TSC access from
> domU will be emulated, which causes a significant perfomance drop for
> workloads that make use of rdtsc.
>
> Add a n
Add an option to control when vTSC emulation will be activated for a
domU with tsc_mode=default. Without such option each TSC access from
domU will be emulated, which causes a significant perfomance drop for
workloads that make use of rdtsc.
Add a new domctl XEN_DOMCTL_set_vtsc_tolerance_khz to ad
