[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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

On 09/30/2014 08:48 PM, Tian, Kevin wrote:
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
* XENPMU_MODE_OFF:  PMU is not virtualized
* XENPMU_MODE_SELF: Guests can access PMU MSRs and receive PMU
* 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
with 'vpmu' argument. An 'off' (or '0') value is equivalent to
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?

No reason at all. They are gone in v13.


Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.