Re: [RFC] [Patch 4/4] lock contention tracking slimmed down

Peter Zijlstra
2007-06-07T06:39:48Z

On Thu, 2007-06-07 at 02:17 +0200, Martin Peschke wrote:
> Ingo Molnar wrote:
> > * Martin Peschke <mp3@de.ibm.com> wrote:
> >
> >> The output has changed from a terribly wide table to an enormously
> >> long list (just the generic way the statistics code prints data).
> >
> > Sigh, why dont you _ask_ before doing such stuff?
>
> A nice diffstat is always worth a try, isn't it?
> And I see other reasons for code sharing.
> Ah, and doing it has been actually quite simple once I had figured out
> what the original code does. :-)
>
> > It is a terribly wide table because that makes it easily greppable
>
> If one looks for contentions of "xtime_lock" within my enormously long list,
> they could issue:
>
> grep -e "xtime_lock contentions" data
>
> and get
>
> xtime_lock contentions 0x17bd2 3327 account_ticks+0x96/0x184
> xtime_lock contentions other 0
>
> for example.
>
> So how is this worse?

How will you find the 5 most contended locks with 1 grep?

It used to be:
grep ":" /proc/lock_stat | head -n 5

lock stat is more about finding who is bad than examining a particular
lock (of course in the process of fixing that lock, that does become
interesting).

Nor was it _that_ wide, it easily fit into an xterm, even on my laptop.