Messages in this thread | | | Date | Thu, 07 Jun 2007 08:59:15 +0200 | From | Martin Peschke <> | Subject | Re: [RFC] [Patch 4/4] lock contention tracking slimmed down |
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Peter Zijlstra wrote: > 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
grep "contention" data |sort -k 4 -n |tail -n 5
&rq->rq_lock_key contentions 0x34c04 613 task_rq_lock+0x64/0xb0 &zone->lock contentions 0x8322e 770 __free_pages_ok+0x1b2/0x534 &zone->lock contentions 0x82828 1017 free_pages_bulk+0x40/0x42c xtime_lock contentions 0x17bd2 3327 account_ticks+0x96/0x184 &inode->i_mutex contentions 0x3273ee 8807 mutex_lock+0x3e/0x4c
Admittedly this gives you the top five contention points, as my prototype tracks this without accounting the total number of contentions for a given lock in another counter.
If the above command line isn't good enough, we could easily put a total contentions counter for each lock back in (see lock_stat_info).
> > 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).
Sure. I guess that applies to most other statistics.
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