Re: [PATCH v2 00/11] KVM in-guest performance monitoring

[David Ahern <daahern@cisco.com>]

On 06/15/2011 02:57 AM, Avi Kivity wrote:
> Okay.  If you do anything interesting with it, please let us know.  I
> only tested the watchdog, 'perf top', and 'perf stat'.
> 

For the following I was using the userspace command from latest
perf-core branch.

cycles H/W event is not working for me, so perf-top did not do much
other than start.

perf-stat -ddd shows a whole lot of 0's - which is interesting. It means
time enabled and time running are non-0, yet the counter value is 0.
cycles and instructions events also show as not counted

Command I was playing with:
  taskset -c 1 chrt -r 1 perf stat -ddd openssl speed aes

Performance counter stats for 'openssl speed aes':

      46111.369065 task-clock                #    0.984 CPUs utilized

               195 context-switches          #    0.000 M/sec

                 0 CPU-migrations            #    0.000 M/sec

               650 page-faults               #    0.000 M/sec

     <not counted> cycles
                 0 stalled-cycles-frontend   #    0.00% frontend cycles
idle    [ 7.63%]
                 0 stalled-cycles-backend    #    0.00% backend  cycles
idle    [12.70%]
     <not counted> instructions
       801,002,999 branches                  #   17.371 M/sec
        [ 8.15%]
         8,491,676 branch-misses             #    1.06% of all branches
        [15.17%]
                 0 L1-dcache-loads           #    0.000 M/sec
        [ 9.23%]
                 0 L1-dcache-load-misses     #    0.00% of all L1-dcache
hits   [ 8.48%]
                 0 LLC-loads                 #    0.000 M/sec
        [13.89%]
                 0 LLC-load-misses           #    0.00% of all LL-cache
hits    [12.47%]
                 0 L1-icache-loads           #    0.000 M/sec
        [ 9.46%]
                 0 L1-icache-load-misses     #    0.00% of all L1-icache
hits   [ 9.44%]
                 0 dTLB-loads                #    0.000 M/sec
        [ 9.59%]
                 0 dTLB-load-misses          #    0.00% of all dTLB
cache hits  [11.00%]
                 0 iTLB-loads                #    0.000 M/sec
        [11.13%]
                 0 iTLB-load-misses          #    0.00% of all iTLB
cache hits  [ 9.73%]
                 0 L1-dcache-prefetches      #    0.000 M/sec
        [10.98%]
                 0 L1-dcache-prefetch-misses #    0.000 M/sec
        [12.51%]

      46.851192693 seconds time elapsed


Also, the numbers for branches and branch-misses just seem wrong
compared to the same command run in the host as well as running
perf-stat in the host on the vcpu thread running openssl (with the vcpu
pinned to a pcpu).

And then reality kicked in and I had to move on to other items.

David