Re: perf lock usage

[Jiri Olsa <jolsa@redhat.com>]

On Wed, Jan 29, 2014 at 07:23:57PM +0530, Sujith Manoharan wrote:
> Jiri Olsa wrote:
> > some of the kernel lock types do not follow the:
> >   acquire
> >   contended
> >   acuired
> >   release
> > 
> > lock state machine, like rcu or spin locks.. and thats what
> > caused most of the bad rates in my tests.
> > 
> > I was recently working on some changes for lock tracing,
> > what stats are you interested in?
> 
> I am trying to see lock usage stats for the ath9k wireless driver.
> Mainly in the transmission path, where normal spin locks
> are acquired.

I was using following code for studying the lock flow,
but it can also display the overhead (but not much in detail)

git tree:
  git://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
  perf/core_lock branch

the usage is sort of described in example here:
https://git.kernel.org/cgit/linux/kernel/git/jolsa/perf.git/commit/?h=perf/core_lock&id=f140425e46b2469b825c12b72507c6f3c539c7dd

so far I've been using the list mode only for checking
the lock flow, but it doesn't seem much useful otherwise..
so I haven't shared it yet

not sure this can be any use for you, but let me know if
you'd need other info

jirka