Re: [Xen-devel] [PATCH v12 for-xen-4.5 11/20] x86/VPMU: Interface for setting PMU mode and flags

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Boris Ostrovsky [mailto:boris.ostrovsky@xxxxxxxxxx]
> Sent: Thursday, September 25, 2014 12:29 PM
> 
> Add runtime interface for setting PMU mode and flags. Three main modes are
> provided:
> * XENPMU_MODE_OFF:  PMU is not virtualized
> * XENPMU_MODE_SELF: Guests can access PMU MSRs and receive PMU
> interrupts.
> * XENPMU_MODE_HV: Same as XENPMU_MODE_SELF for non-proviledged
> guests, dom0
>   can profile itself and the hypervisor.
> 
> Note that PMU modes are different from what can be provided at Xen's boot
> line
> with 'vpmu' argument. An 'off' (or '0') value is equivalent to
> XENPMU_MODE_OFF.
> Any other value, on the other hand, will cause VPMU mode to be set to
> XENPMU_MODE_SELF during boot.
> 
> For feature flags only Intel's BTS is currently supported.
> 
> Mode and flags are set via HYPERVISOR_xenpmu_op hypercall.
> 
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

In general it's OK to me:
Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>

Just a small comment:

> +static void vpmu_sched_checkin(unsigned long unused)
> +{
> +    atomic_inc(&vpmu_sched_counter);
> +}
> +
> +static int vpmu_force_context_switch(void)
> +{
> +    unsigned i, j, allbutself_num, mycpu;
> +    static s_time_t start, now;

any reason of such static variables when there's no continuation any more?

Thanks
Kevin

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