[libvirt] [PATCH 7/9] perf: add page_faults_maj software perf event support
Nitesh Konkar
niteshkonkar.libvirt at gmail.com
Mon Feb 13 06:49:38 UTC 2017
On Fri, Feb 10, 2017 at 3:22 AM, John Ferlan <jferlan at redhat.com> wrote:
>
>
> On 01/27/2017 06:01 AM, Nitesh Konkar wrote:
> > This patch adds support and documentation
> > for the page_faults_maj perf event.
> >
> > Signed-off-by: Nitesh Konkar <nitkon12 at linux.vnet.ibm.com>
> > ---
> > docs/formatdomain.html.in | 7 +++++++
> > docs/news.xml | 4 ++--
> > docs/schemas/domaincommon.rng | 1 +
> > include/libvirt/libvirt-domain.h | 10 ++++++++++
> > src/libvirt-domain.c | 3 +++
> > 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 | 5 +++++
> > 10 files changed, 35 insertions(+), 3 deletions(-)
> >
>
> NB: Similar comments from the page_faults_min...
>
> > diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
> > index 1857168..50a6bdb 100644
> > --- a/docs/formatdomain.html.in
> > +++ b/docs/formatdomain.html.in
> > @@ -1943,6 +1943,7 @@
> > <event name='context_switches' enabled='no'/>
> > <event name='cpu_migrations' enabled='no'/>
> > <event name='page_faults_min' enabled='no'/>
> > + <event name='page_faults_maj' enabled='no'/>
> > </perf>
> > ...
> > </pre>
> > @@ -2052,6 +2053,12 @@
> > platform</td>
> > <td><code>perf.page_faults_min</code></td>
> > </tr>
> > + <tr>
> > + <td><code>page_faults_maj</code></td>
> > + <td>the count of major page faults by applications running on the
> > + platform</td>
> > + <td><code>perf.page_faults_maj</code></td>
> > + </tr>
>
> As already noted in patch 3... is maj+min the same as what patch 3
> provides?
>
maj+min is not always exactly the same as page faults. Sometimes there is a
small offset
value.
Eg: perf record -a --event={page-faults,major-faults,minor-faults}
47
page-faults
0
major-faults
46 minor-faults
Offset by 1
Eg: virsh domstats --perf
Domain: 'Fedora'
perf.page_faults=890
perf.page_faults_min=890
perf.page_faults_maj=0
Here maj+min=page_faults
Thus are all necessary?
>
I am not sure on this part. Probably yes as we dont want
the user to add min+maj to get (approx)total page faults.
>
> > </table>
> >
> > <h3><a name="elementsDevices">Devices</a></h3>
> > diff --git a/docs/news.xml b/docs/news.xml
> > index 0e7c0d2..fe533f2 100644
> > --- a/docs/news.xml
> > +++ b/docs/news.xml
> > @@ -138,8 +138,8 @@
> > executed, branch misses, bus cycles, stalled frontend
> > cpu cycles, stalled backend cpu cycles, ref cpu cycles,
> > cpu clock, task clock, page faults, context switches,
> > - cpu migrations and page faults min by applications
> > - running on the platform.
> > + cpu migrations, page faults min and page faults maj by
> > + applications running on the platform.
>
> Remove news.xml
>
> > </description>
> > </change>
> > <change>
> > diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.
> rng
> > index f30ec0d..5f986d6 100644
> > --- a/docs/schemas/domaincommon.rng
> > +++ b/docs/schemas/domaincommon.rng
> > @@ -439,6 +439,7 @@
> > <value>context_switches</value>
> > <value>cpu_migrations</value>
> > <value>page_faults_min</value>
> > + <value>page_faults_maj</value>
> > </choice>
> > </attribute>
> > <attribute name="enabled">
> > diff --git a/include/libvirt/libvirt-domain.h b/include/libvirt/libvirt-
> domain.h
> > index 108591a..d16200f 100644
> > --- a/include/libvirt/libvirt-domain.h
> > +++ b/include/libvirt/libvirt-domain.h
> > @@ -2248,6 +2248,16 @@ void virDomainStatsRecordListFree(virDomainStatsRecordPtr
> *stats);
> > */
> > # define VIR_PERF_PARAM_PAGE_FAULTS_MIN "page_faults_min"
> >
> > +/**
> > + * VIR_PERF_PARAM_PAGE_FAULTS_MAJ:
> > + *
> > + * Macro for typed parameter name that represents page_faults_maj
> > + * perf event which can be used to measure the count of major page
> > + * faults by applications running on the platform. It corresponds
> > + * to the "perf.page_faults_maj" field in the *Stats APIs.
> > + */
> > +# define VIR_PERF_PARAM_PAGE_FAULTS_MAJ "page_faults_maj"
> > +
> > int virDomainGetPerfEvents(virDomainPtr dom,
> > virTypedParameterPtr *params,
> > int *nparams,
> > diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c
> > index 1be385e..1d7c181 100644
> > --- a/src/libvirt-domain.c
> > +++ b/src/libvirt-domain.c
> > @@ -11265,6 +11265,9 @@ virConnectGetDomainCapabilities(virConnectPtr
> conn,
> > * "perf.page_faults_min" - The count of minor page faults as
> unsigned long
> > * long. It is produced by the
> page_faults_min
> > * perf event.
> > + * "perf.page_faults_maj" - The count of major page faults as
> unsigned long
> > + * long. It is produced by the
> page_faults_maj
> > + * 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 4f24fa6..c88bf5a 100644
> > --- a/src/qemu/qemu_driver.c
> > +++ b/src/qemu/qemu_driver.c
> > @@ -9555,6 +9555,7 @@ qemuDomainSetPerfEvents(virDomainPtr dom,
> > VIR_PERF_PARAM_CONTEXT_SWITCHES,
> VIR_TYPED_PARAM_BOOLEAN,
> > VIR_PERF_PARAM_CPU_MIGRATIONS,
> VIR_TYPED_PARAM_BOOLEAN,
> > VIR_PERF_PARAM_PAGE_FAULTS_MIN,
> VIR_TYPED_PARAM_BOOLEAN,
> > + VIR_PERF_PARAM_PAGE_FAULTS_MAJ,
> VIR_TYPED_PARAM_BOOLEAN,
> > NULL) < 0)
> > return -1;
> >
> > diff --git a/src/util/virperf.c b/src/util/virperf.c
> > index c839b04..37f61e2 100644
> > --- a/src/util/virperf.c
> > +++ b/src/util/virperf.c
> > @@ -46,7 +46,7 @@ VIR_ENUM_IMPL(virPerfEvent, VIR_PERF_EVENT_LAST,
> > "stalled_cycles_backend", "ref_cpu_cycles",
> > "cpu_clock", "task_clock", "page_faults",
> > "context_switches", "cpu_migrations",
> > - "page_faults_min");
> > + "page_faults_min", "page_faults_maj");
> >
> > struct virPerfEvent {
> > int type;
> > @@ -133,6 +133,9 @@ static struct virPerfEventAttr attrs[] = {
> > {.type = VIR_PERF_EVENT_PAGE_FAULTS_MIN,
> > .attrType = PERF_TYPE_SOFTWARE,
> > .attrConfig = PERF_COUNT_SW_PAGE_FAULTS_MIN},
> > + {.type = VIR_PERF_EVENT_PAGE_FAULTS_MAJ,
> > + .attrType = PERF_TYPE_SOFTWARE,
> > + .attrConfig = PERF_COUNT_SW_PAGE_FAULTS_MAJ},
> > };
> > typedef struct virPerfEventAttr *virPerfEventAttrPtr;
> >
> > diff --git a/src/util/virperf.h b/src/util/virperf.h
> > index aec352b..e99c870 100644
> > --- a/src/util/virperf.h
> > +++ b/src/util/virperf.h
> > @@ -53,6 +53,7 @@ typedef enum {
> > VIR_PERF_EVENT_CONTEXT_SWITCHES, /* Count of context switches */
> > VIR_PERF_EVENT_CPU_MIGRATIONS, /* Count of cpu migrations */
> > VIR_PERF_EVENT_PAGE_FAULTS_MIN, /* Count of minor page faults */
> > + VIR_PERF_EVENT_PAGE_FAULTS_MAJ, /* Count of major page faults */
> >
> > VIR_PERF_EVENT_LAST
> > } virPerfEventType;
> > diff --git a/tests/genericxml2xmlindata/generic-perf.xml
> b/tests/genericxml2xmlindata/generic-perf.xml
> > index 62ad973..a5b6dfb 100644
> > --- a/tests/genericxml2xmlindata/generic-perf.xml
> > +++ b/tests/genericxml2xmlindata/generic-perf.xml
> > @@ -32,6 +32,7 @@
> > <event name='context_switches' enabled='yes'/>
> > <event name='cpu_migrations' enabled='yes'/>
> > <event name='page_faults_min' enabled='yes'/>
> > + <event name='page_faults_maj' enabled='yes'/>
> > </perf>
> > <devices>
> > </devices>
> > diff --git a/tools/virsh.pod b/tools/virsh.pod
> > index 4eb689e..d6bec4d 100644
> > --- a/tools/virsh.pod
> > +++ b/tools/virsh.pod
> > @@ -952,6 +952,7 @@ I<--perf> returns the statistics of all enabled perf
> events:
> > "perf.context_switches" - the count of context switches
> > "perf.cpu_migrations" - the count of cpu migrations
> > "perf.page_faults_min" - the count of minor page faults
> > +"perf.page_faults_maj" - the count of major page faults
> >
> > See the B<perf> command for more details about each event.
> >
> > @@ -2331,6 +2332,10 @@ B<Valid perf event names>
> > the page was present in the page cache, and
> therefore the
> > fault avoided loading it from storage, by
> applications
> > running on the platform
> > + page_faults_maj - Provides the count of major page faults, that is,
> where
> > + the page was not present in the page cache, and
> therefore
> > + had to be fetched from storage, by applications
> > + running on the platform
>
> The min/maj descriptions here are a bit more wordy. It does help, but I
> wonder now is this the wrong place. That is should the longer
> description be in the API so that the rendered API docs get a nice long
> description and the virsh output remains somewhat terse.
>
> It really is up to you to decide, but I'm leaning towards better API doc
> descriptions...
>
Okay. Lets have a longer description in API and terse decription in virsh
output.
>
> John
> >
> > B<Note>: The statistics can be retrieved using the B<domstats> command
> using
> > the I<--perf> flag.
> >
>
Thanks for all the review comments.
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