Hi,
On 13.2.2020 20.44, Dylan Baker wrote:
I actually spent a bunch of time toying with PGO a couple of years ago. I got
the guidance all working and was able to train it, but what we found was that it
made the specific workloads we threw at it much faster, but it made every real
world use case
The GCC wiki says:
"GCC uses execution profiles consisting of basic block and edge frequency
counts to guide optimizations such as instruction scheduling, basic block
reordering, function splitting, and register allocation."
More info here:
https://gcc.gnu.org/wiki/AutoFDO/Tutorial
Timur
On
Yeah I guess it reduces instruction cache misses, but then other codepaths
are likely to get more misses.
Does it do anything smarter?
Marek
On Thu., Feb. 13, 2020, 17:52 Dave Airlie, wrote:
> On Fri, 14 Feb 2020 at 08:22, Marek Olšák wrote:
> >
> > I wonder what PGO really does other than
On Fri, 14 Feb 2020 at 08:22, Marek Olšák wrote:
>
> I wonder what PGO really does other than placing likely/unlikely.
With LTO it can do a lot more, like grouping hot functions into closer
regions so they avoid TLB misses and faults etc.
Dave.
___
I wonder what PGO really does other than placing likely/unlikely.
Marek
On Thu., Feb. 13, 2020, 13:43 Dylan Baker, wrote:
> I actually spent a bunch of time toying with PGO a couple of years ago. I
> got
> the guidance all working and was able to train it, but what we found was
> that it
>
I actually spent a bunch of time toying with PGO a couple of years ago. I got
the guidance all working and was able to train it, but what we found was that it
made the specific workloads we threw at it much faster, but it made every real
world use case I tried (playing a game, running piglit,
[Forked from the other thread]
Guys, we could run some simple tests similar to piglit/drawoverhead as the
last step of the pgo=generate build. Tests like that should exercise the
most common codepaths in drivers. We could add subtests that we care about
the most.
Marek
On Thu., Feb. 13, 2020,
