[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v1] xen: acpi: upload _PSD info for offline CPUs too
On 03/07/2018 05:51 PM, Boris Ostrovsky wrote: > 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"? > Yeah, probably clearer to use that. >> 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@xxxxxxxxxx> >> --- >> 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. > OK, I'll respin with exporting this from drivers/acpi. FWIW I copied solely for backportability purposes provided that hardware with SW_ANY or SW_ALL and current stable kernels is a little broken. Joao _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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