Re: [PATCH] - kernel profiler & spinlock_contention

Jack Steiner
2003-11-26T19:02:30Z

On Wed, Nov 26, 2003 at 09:31:02AM -0800, David Mosberger wrote:
> >>>>> On Wed, 26 Nov 2003 09:23:10 -0600, Jack Steiner <steiner@sgi.com> said:
>
> Jack> Profiling is more useful if addresses in spinlock_contention
> Jack> were attributed to the caller of spinlock_contention.
>
> Execuse the language, but I'm reading:
>
> my tools suck so let's make the kernel suck!

I dont quite agree. The way it work right now, profiling on large
systems is useless. The single hotest spot in the kernel is
spinlock_contention & there is no clue why. The patch makes
the kernel work the way it did before spinning for locks was
moved out-of-line. I think that is a big improvement.

However, if your new tools allows me to determine the caller
of spinlock_contention (I'm guessing that it does), that is even better!!
If a prerelease version of the tools is available, I'll be happy
to try it on our system

>
> Let's defer this discussion until next week, when I had a chance to
> release my profiling tool. I think you'll then agree that it's much
> better to leave the code as is. In fact, we should also have an
> out-of-line contention handler for the read/write locks.

Agree!

>
> --david

--
Thanks

Jack Steiner (steiner@sgi.com) 651-683-5302
Principal Engineer SGI - Silicon Graphics, Inc.