Messages in this thread | | | Subject | Re: [PATCH v1] xen: acpi: upload _PSD info for offline CPUs too | From | Boris Ostrovsky <> | Date | Wed, 7 Mar 2018 12:51:12 -0500 |
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On 03/06/2018 03:12 PM, Joao Martins wrote: > All uploaded PM data from offline CPUs takes the info from vCPU 0 and
"offline" may not be the right term here. Maybe "non-dom0"?
> changing only the acpi_id. For processors which P-state coordination type > is HW_ALL (0xFD) it is OK to upload bogus P-state dependency information > (_PSD), because Xen will ignore cpufreq domains existence. > > Albeit for hardware exposing Px coordination types as SW_ANY or SW_ALL, > this will have some unintended side effects. Effectively, it will look at > the P-state domain existence and *if it already exists* it will skip the > acpi-cpufreq initialization and thus inherit the policy from the first CPU > in the cpufreq domain. This will finally lead to the original cpu not > changing target freq to P0 other than the first in the domain. Which will > make turbo boost not getting enabled (e.g. for 'performance' governor) for > all cpus. > > This patch fixes that, by also evaluating _PSD when enumerating all ACPI > procesors (online and offline) and always uploading the correct P-State > dependency up to Xen. > > Signed-off-by: Joao Martins <joao.m.martins@oracle.com> > --- > xen_processor_get_psd() is taken from acpi_processor_get_psd() > (drivers/acpi/processor_perflib.c) simply because only Xen Dom0 needs > to handle vcpus != pcpus. If preferred I could try exporting that API > instead and use it here.
I think this would be a preferable approach.
-boris
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