Hi Shannon,

On Fri, Sep 11, 2015 at 04:54:53PM +0800, Shannon Zhao wrote:

From: Shannon Zhao <redacted>

This patchset adds guest PMU support for KVM on ARM64. It takes
trap-and-emulate approach. When guest wants to monitor one event, it
will be trapped by KVM and KVM will call perf_event API to create a perf
event and call relevant perf_event APIs to get the count value of event.

Use perf to test this patchset in guest. When using "perf list", it
shows the list of the hardware events and hardware cache events perf
supports. Then use "perf stat -e EVENT" to monitor some event. For
example, use "perf stat -e cycles" to count cpu cycles and
"perf stat -e cache-misses" to count cache misses.

Below are the outputs of "perf stat -r 5 sleep 5" when running in host
and guest.

Host:
 Performance counter stats for 'sleep 5' (5 runs):

          0.551428      task-clock (msec)         #    0.000 CPUs utilized            ( +-  0.91% )
                 1      context-switches          #    0.002 M/sec
                 0      cpu-migrations            #    0.000 K/sec
                48      page-faults               #    0.088 M/sec                    ( +-  1.05% )
           1150265      cycles                    #    2.086 GHz                      ( +-  0.92% )
   <not supported>      stalled-cycles-frontend
   <not supported>      stalled-cycles-backend
            526398      instructions              #    0.46  insns per cycle          ( +-  0.89% )
   <not supported>      branches
              9485      branch-misses             #   17.201 M/sec                    ( +-  2.35% )

       5.000831616 seconds time elapsed                                          ( +-  0.00% )

Guest:
 Performance counter stats for 'sleep 5' (5 runs):

          0.730868      task-clock (msec)         #    0.000 CPUs utilized            ( +-  1.13% )
                 1      context-switches          #    0.001 M/sec
                 0      cpu-migrations            #    0.000 K/sec
                48      page-faults               #    0.065 M/sec                    ( +-  0.42% )
           1642982      cycles                    #    2.248 GHz                      ( +-  1.04% )
   <not supported>      stalled-cycles-frontend
   <not supported>      stalled-cycles-backend
            637964      instructions              #    0.39  insns per cycle          ( +-  0.65% )
   <not supported>      branches
             10377      branch-misses             #   14.198 M/sec                    ( +-  1.09% )

       5.001289068 seconds time elapsed                                          ( +-  0.00% )

This patchset can be fetched from [1] and the relevant QEMU version for
test can be fetched from [2].

Is there a changelog for this patch set somewhere?

If not, can you include this in v3 addressing Marc's comments?

Thanks,
-Christoffer