<div dir="ltr"> <div class="gmail_extra"> <div class="gmail_quote">On Mon, Feb 13, 2017 at 8:14 PM, John Ferlan <<a href="mailto:jferlan@redhat.com" target="_blank">jferlan@redhat.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> On 02/13/2017 01:49 AM, Nitesh Konkar wrote: > > > > On Fri, Feb 10, 2017 at 3:22 AM, John Ferlan <<a href="mailto:jferlan@redhat.com" target="_blank">jferlan@redhat.com</a> > <mailto:<a href="mailto:jferlan@redhat.com" target="_blank">jferlan@redhat.com</a>>> 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 <<a href="mailto:nitkon12@linux.vnet.ibm.com" target="_blank">nitkon12@linux.vnet.ibm.com</a> <mailto:<a href="mailto:nitkon12@linux.vnet.ibm.com" target="_blank">nitkon12@linux.vnet.ibm.com</a>>> > > --- > > docs/<a href="http://formatdomain.html.in" rel="noreferrer" target="_blank">formatdomain.html.in</a> <<a href="http://formatdomain.html.in" rel="noreferrer" target="_blank">http://formatdomain.html.in</a>> > | 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/<a href="http://formatdomain.html.in" rel="noreferrer" target="_blank">formatdomain.html.in</a> <<a href="http://formatdomain.html.in" rel="noreferrer" target="_blank">http://formatdomain.html.in</a>> > b/docs/<a href="http://formatdomain.html.in" rel="noreferrer" target="_blank">formatdomain.html.in</a> <<a href="http://formatdomain.html.in" rel="noreferrer" target="_blank">http://formatdomain.html.in</a>> > > index 1857168..50a6bdb 100644 > > --- a/docs/<a href="http://formatdomain.html.in" rel="noreferrer" target="_blank">formatdomain.html.in</a> <<a href="http://formatdomain.html.in" rel="noreferrer" target="_blank">http://formatdomain.html.in</a>> > > +++ b/docs/<a href="http://formatdomain.html.in" rel="noreferrer" target="_blank">formatdomain.html.in</a> <<a href="http://formatdomain.html.in" rel="noreferrer" target="_blank">http://formatdomain.html.in</a>> <div><div class="gmail-m_-211566420636597459gmail-h5">> > @@ -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. > > </div></div>I don't mind all 3 being present... still if I'm going to ask the question, then someone getting the stats will ask the question... they may also wonder why maj+min != total. Perhaps something you could dig deeper on with the kernel code descriptions that are setting the value. My assumption is it's the "time" of the sample. That is a total page fault could have been counted even though it hadn't been counted as a maj or min page fault. </blockquote><div> I looked into the kernel code in /arch/x86/mm/fault.c and also confirmed from </div><div>the #perf IRC that maj+min != total is valid. This is because not all </div><div>page faults fall in maj/min category. Some maybe invalid page faults(invalid address generated) whereas some pagefaults after occuring are not serviced due to lock contention so as to avoid a deadlock at that instance, thus being counted in total but not in min/maj faults. </div><div>Also, shd i follow the comment pattern as shown </div><div>in ur patch under review, in /virsh.pod ? </div><div>Thnx. </div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> John </blockquote></div> </div></div>