Peter Zijlstra wrote:
On Thu, 2007-06-07 at 02:17 +0200, Martin Peschke wrote:
Ingo Molnar wrote:
* Martin Peschke <[email protected]> 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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