[Mesa-dev] [PATCH 3/4] winsys/radeon: Keep bo statistics

[Lauri Kasanen]

On Wed, 8 Jan 2014 19:03:53 +0100
Marek Olšák <maraeo at gmail.com> wrote:

> On Wed, Jan 8, 2014 at 6:21 PM, Lauri Kasanen <cand at gmx.com> wrote:
> > On Wed, 8 Jan 2014 15:54:04 +0100
> > Marek Olšák <maraeo at gmail.com> wrote:
> >> It's not accurate at all, it's actually pretty random. The stats
> >> should not be called "num_reads" and "num_writes", they should be
> >> called "num_state_changes", and the number of resource state changes
> >> has nothing to do with how the resources affect GPU performance. You
> >> might get a pretty high score for unimportant resources with your
> >> approach. It's as useful as assigning a random number to each
> >> resource.
> >
> > Yes, more accurate names would be "times_bound_for_reads" and
> > "times_bound_for_writes", but those are too long names for my taste ;)
> 
> Yeah, and those 2 are completely useless, because the number of times
> a resource is bound is irrelevant and won't help us in any way. Like I
> said, you could just assign a random number to "times_bound_for_*" in
> radeon_drm_cs_flush and it would perform the same or better, because
> random statistics are better than bad statistics.

Can you elaborate? How often does an app bind a texture without
bothering to read from it? The engines I've worked with take care to
unbind textures they are not using.

The read pattern is half, but the fact that it's being read is the
other half of the equation.

> In other words, I won't accept your "num_reads/writes" counters in the
> current form.

Ok.

- Lauri