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

Martin Peschke
2007-06-07T00:18:01Z

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?

> but still watchable in one chunk in a sufficiently zoomed out xterm.

I am wondering whether we really want to reject kernel patches on the basis of
this reasoning, disregarding any other point why a patch might be helpful.

> Please preserve this output format

I understand why everybody likes their format most. It's always made to measure.
Chosing a different - or common - format didn't happen in bad faith.

Made to measure file format doesn't work well once we start abstracting out this
functionality. And I feel that was expected too much of a low level kernel ABI
piece.

I would like to add that usuability doesn't necessarily suffer if statistics for
some brand new gadget look somewhat familiar and similar to other statistics one
has encountered earlier.

>, quite some work went into it - NACK :-(

Considering the amount of code.. ;-) I am sorry.

But seriously, did you consider using some user space tool or script to
format this stuff the way you like it - similar to the way the powertop tool
reshuffles timer_stats data found in a proc file, for example?

The format of an enormously long list has been thought out keeping this
particular requirement in mind.

Martin