Anybody who had done benchmarks on enabling LTO and PGO?

[odd cairn]

does LTO and PGO really improve performance?
would be very nice if somebody had done a benchmark before and post it here

[left hull]

Benchmarks of what?

There is compiler benchmark on github (i dont remember how its called), you can check it

You cant measure performance of daily usage lol

[odd cairn]

idk

how fast firefox opens?

if it doesn't increase performance

I ain't doubling my compile times then

[left hull]

Its always slow for me

I had pgo and lto enabled globally, but then i realized that i cant compile gcc

LTO doesn't really slow down compilation, so i will enable it globally ig

[inner oxide]

I did a rough one

[inner oxide]

Yes it does

2 to 3 times longer

[left hull]

What

Thats FullLTO

ThinLTO is hella fast

[inner oxide]

And thin can

Recorded with gcc

Thin by default

https://youtu.be/umiVJdnZxMw @odd cairn

[left hull]

LTO and GCC is the worst combination ever

[inner oxide]

Explain

[left hull]

I cant compile gcc because it's LTO implementation sucks ass

It takes over five hours to compile three stages

[inner oxide]

That's you I'm afraid the rest of us have no issue

Pgo on GCC doesn't seem to do much though

I'm curious now so benchmarks incoming

[odd cairn]

quick question

have you tried with enabling rust optimizations?

so like this:

RUSTFLAGS="-C target-cpu=native -C opt-level=2"

[inner oxide]

Why would you lower the opt level lower then default

[odd cairn]

?

is it 3 by default?

[left hull]

Well, if you could google, you could find answer immediately

[inner oxide]

Yep

We dont explain this well in the rust article thougj

@left hull mind updating please?

[left hull]

You mean wiki page?

[inner oxide]

Yes please

[left hull]

Submitted change. And there is no review?

https://wiki.gentoo.org/wiki/Rust#Optimization_level

[inner oxide]

❤️

[odd cairn]

ah ok

[inner oxide]

https://youtu.be/VnnEEBbm79Q

[jaunty apex]

I did a test with chromium. Default speeds where ~64k on silver bench. When I compiled with o3 pgo and lto I got 72k

The compile also took 3 hours longer fyi

[odd cairn]

meh

definitely faster

but not worth the additional compile times

[inner oxide]

Web browsers are normally worth it

[left hull]

My chromium simply segfaulted after 13 hours of compilation

[dreamy gyro]

i have benchmark usb with void

but what benchmark do you need

[steel jetty]

For FFmpeg, only SVT-AV1 experiences a perf uplift worth a damn with ThinLTO, about 30%.