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Re: [libvirt] [PATCH 5/9] perf: add cpu_migrations software perf event support




On 01/27/2017 06:01 AM, Nitesh Konkar wrote:
> This patch adds support and documentation
> for the cpu_migrations perf event.
> 
> Signed-off-by: Nitesh Konkar <nitkon12 linux vnet ibm com>
> ---
>  docs/formatdomain.html.in                   | 6 ++++++
>  docs/news.xml                               | 4 ++--
>  docs/schemas/domaincommon.rng               | 1 +
>  include/libvirt/libvirt-domain.h            | 9 +++++++++
>  src/libvirt-domain.c                        | 5 ++++-
>  src/qemu/qemu_driver.c                      | 1 +
>  src/util/virperf.c                          | 5 ++++-
>  src/util/virperf.h                          | 1 +
>  tests/genericxml2xmlindata/generic-perf.xml | 1 +
>  tools/virsh.pod                             | 4 ++++
>  10 files changed, 33 insertions(+), 4 deletions(-)
> 
> diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
> index 4ed6e02..f0efab1 100644
> --- a/docs/formatdomain.html.in
> +++ b/docs/formatdomain.html.in
> @@ -1941,6 +1941,7 @@
>    &lt;event name='task_clock' enabled='no'/&gt;
>    &lt;event name='page_faults' enabled='no'/&gt;
>    &lt;event name='context_switches' enabled='no'/&gt;
> +  &lt;event name='cpu_migrations' enabled='no'/&gt;
>  &lt;/perf&gt;
>  ...
>  </pre>
> @@ -2039,6 +2040,11 @@
>        <td>the count of context switches by applications running on the platform</td>
>        <td><code>perf.context_switches</code></td>
>      </tr>
> +    <tr>
> +      <td><code>cpu_migrations</code></td>
> +      <td>the count of cpu migrations by applications running on the platform</td>
> +      <td><code>perf.cpu_migrations</code></td>
> +    </tr>

Not sure "count of cpu migrations by applictions" conveys enough
meaning. Is this something applications can control? Is this one of
those things where applications may want to "pin" to [a] specific cpu[s]?

>    </table>
>  
>      <h3><a name="elementsDevices">Devices</a></h3>
> diff --git a/docs/news.xml b/docs/news.xml
> index fb872f5..0489c42 100644
> --- a/docs/news.xml
> +++ b/docs/news.xml
> @@ -137,8 +137,8 @@
>            Add support to get the count of branch instructions
>            executed, branch misses, bus cycles, stalled frontend
>            cpu cycles, stalled backend cpu cycles, ref cpu cycles,
> -          cpu clock, task clock, page faults and context switches
> -          by applications running on the platform.
> +          cpu clock, task clock, page faults, context switches and
> +          cpu migrations by applications running on the platform.

Remove news.xml from here.

>          </description>
>        </change>
>        <change>
> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
> index e4e1358..5bd06cb 100644
> --- a/docs/schemas/domaincommon.rng
> +++ b/docs/schemas/domaincommon.rng
> @@ -437,6 +437,7 @@
>                <value>task_clock</value>
>                <value>page_faults</value>
>                <value>context_switches</value>
> +              <value>cpu_migrations</value>
>              </choice>
>            </attribute>
>            <attribute name="enabled">
> diff --git a/include/libvirt/libvirt-domain.h b/include/libvirt/libvirt-domain.h
> index e71bfa7..b4abdb0 100644
> --- a/include/libvirt/libvirt-domain.h
> +++ b/include/libvirt/libvirt-domain.h
> @@ -2228,6 +2228,15 @@ void virDomainStatsRecordListFree(virDomainStatsRecordPtr *stats);
>   */
>  # define VIR_PERF_PARAM_CONTEXT_SWITCHES "context_switches"
>  
> +/**
> + * VIR_PERF_PARAM_CPU_MIGRATIONS:
> + *
> + * Macro for typed parameter name that represents cpu_migrations
> + * perf event which can be used to measure the count of cpu
> + * migrations by applications running on the platform. It corresponds
> + * to the "perf.cpu_migrations" field in the *Stats APIs.
> + */
> +# define VIR_PERF_PARAM_CPU_MIGRATIONS "cpu_migrations"
>  
>  int virDomainGetPerfEvents(virDomainPtr dom,
>                             virTypedParameterPtr *params,
> diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c
> index 42720f1..d063414 100644
> --- a/src/libvirt-domain.c
> +++ b/src/libvirt-domain.c
> @@ -11255,10 +11255,13 @@ virConnectGetDomainCapabilities(virConnectPtr conn,
>   *     "perf.task_clock" - The count of task clock as unsigned long long. It is
>   *                         produced by the task_clock perf event.
>   *     "perf.page_faults" - The count of page faults as unsigned long long. It is
> - *                         produced by the page_faults perf event.
> + *                          produced by the page_faults perf event.
>   *     "perf.context_switches" - The count of context switches as unsigned long
>   *                               long. It is produced by the context_switches
>   *                               perf event.
> + *     "perf.cpu_migrations" - The count of cpu migrations as unsigned long
> + *                             long. It is produced by the cpu_migrations
> + *                             perf event.
>   *
>   * Note that entire stats groups or individual stat fields may be missing from
>   * the output in case they are not supported by the given hypervisor, are not
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index c579b61..3fb7032 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -9553,6 +9553,7 @@ qemuDomainSetPerfEvents(virDomainPtr dom,
>                                 VIR_PERF_PARAM_TASK_CLOCK, VIR_TYPED_PARAM_BOOLEAN,
>                                 VIR_PERF_PARAM_PAGE_FAULTS, VIR_TYPED_PARAM_BOOLEAN,
>                                 VIR_PERF_PARAM_CONTEXT_SWITCHES, VIR_TYPED_PARAM_BOOLEAN,
> +                               VIR_PERF_PARAM_CPU_MIGRATIONS, VIR_TYPED_PARAM_BOOLEAN,
>                                 NULL) < 0)
>          return -1;
>  
> diff --git a/src/util/virperf.c b/src/util/virperf.c
> index c004061..4559845 100644
> --- a/src/util/virperf.c
> +++ b/src/util/virperf.c
> @@ -45,7 +45,7 @@ VIR_ENUM_IMPL(virPerfEvent, VIR_PERF_EVENT_LAST,
>                "bus_cycles", "stalled_cycles_frontend",
>                "stalled_cycles_backend", "ref_cpu_cycles",
>                "cpu_clock", "task_clock", "page_faults",
> -              "context_switches");
> +              "context_switches", "cpu_migrations");
>  
>  struct virPerfEvent {
>      int type;
> @@ -126,6 +126,9 @@ static struct virPerfEventAttr attrs[] = {
>      {.type = VIR_PERF_EVENT_CONTEXT_SWITCHES,
>       .attrType = PERF_TYPE_SOFTWARE,
>       .attrConfig = PERF_COUNT_SW_CONTEXT_SWITCHES},
> +    {.type = VIR_PERF_EVENT_CPU_MIGRATIONS,
> +     .attrType = PERF_TYPE_SOFTWARE,
> +     .attrConfig = PERF_COUNT_SW_CPU_MIGRATIONS},
>  };
>  typedef struct virPerfEventAttr *virPerfEventAttrPtr;
>  
> diff --git a/src/util/virperf.h b/src/util/virperf.h
> index b937d9a..b769ebc 100644
> --- a/src/util/virperf.h
> +++ b/src/util/virperf.h
> @@ -51,6 +51,7 @@ typedef enum {
>      VIR_PERF_EVENT_TASK_CLOCK,   /* Count of task clock */
>      VIR_PERF_EVENT_PAGE_FAULTS,   /* Count of page faults */
>      VIR_PERF_EVENT_CONTEXT_SWITCHES,   /* Count of context switches */
> +    VIR_PERF_EVENT_CPU_MIGRATIONS,   /* Count of cpu migrations */
>  
>      VIR_PERF_EVENT_LAST
>  } virPerfEventType;
> diff --git a/tests/genericxml2xmlindata/generic-perf.xml b/tests/genericxml2xmlindata/generic-perf.xml
> index 29a2273..f856318 100644
> --- a/tests/genericxml2xmlindata/generic-perf.xml
> +++ b/tests/genericxml2xmlindata/generic-perf.xml
> @@ -30,6 +30,7 @@
>      <event name='task_clock' enabled='yes'/>
>      <event name='page_faults' enabled='yes'/>
>      <event name='context_switches' enabled='yes'/>
> +    <event name='cpu_migrations' enabled='yes'/>
>    </perf>
>    <devices>
>    </devices>
> diff --git a/tools/virsh.pod b/tools/virsh.pod
> index d0bf016..a5e8ccd 100644
> --- a/tools/virsh.pod
> +++ b/tools/virsh.pod
> @@ -950,6 +950,7 @@ I<--perf> returns the statistics of all enabled perf events:
>  "perf.task_clock" - the count of task clock
>  "perf.page_faults" - the count of page faults
>  "perf.context_switches" - the count of context switches
> +"perf.cpu_migrations" - the count of cpu migrations
>  
>  See the B<perf> command for more details about each event.
>  
> @@ -2322,6 +2323,9 @@ B<Valid perf event names>
>                  running on the platform
>    context_switches - Provides the count of context switches by applications
>                       running on the platform
> +  cpu_migrations - Provides the count of cpu migrations, that is, where the
> +                   process moved from one logical processor to another, by
> +                   applications running on the platform

and this too goes beyond the 80 column...

John
>  
>  B<Note>: The statistics can be retrieved using the B<domstats> command using
>  the I<--perf> flag.
> 


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