A53 is not a great core, and seemingly no compiler targets it well. Back at el goog, ChromeOS team had an intern who used a cycle-accurate model of it to find that android's AOT compiler produced shit code for it when multiplies were involved. A small patch to the AOT compiler produced measurable perf improvement in most android workloads on A53, costing no perf on A57/A72. This patch was, of course, not shipped (politics).
BoingBoomTschak•9mo ago
Could you expand on the "politics" part? I can't imagine the reason why. I mean, if you had said "suits thought this wasn't business relevant" or something, I'd have believed it.
dmitrygr•9mo ago
The intern was in the ChromeOS team, the fix would have needed to go into android. Those two teams were always in a bit of "stay in your lane, buddy" relationship.
saagarjha•9mo ago
I continue to maintain that Google should adopt negative peer bonuses
mtklein•9mo ago
"The peer malus" - Frederic Beal
gessha•9mo ago
And that will result increased tension between the teams “downvoting each other”.
Maybe this way Google will truly become a Microsoft-type of company.
saagarjha•9mo ago
Is it not there already?
jjmarr•9mo ago
I thought the fabled monorepo was supposed to prevent this?
nullpoint420•9mo ago
IIRC, both Android and Chrome(OS) upstream are not in the google3 monorepo.
djmips•9mo ago
The article also mentions how the llvm-mca is inaccurate for the A53. And furthermore LLVM compilers will do poorly
"...any compiler that is using LLVM to optimize machine code (such as the Rust compiler or clang) will not do very well for the A53, since it’s essentially trying to optimize code using a wrong CPU model. "
dmitrygr•9mo ago
BoingBoomTschak•9mo ago
dmitrygr•9mo ago
saagarjha•9mo ago
mtklein•9mo ago
gessha•9mo ago
Maybe this way Google will truly become a Microsoft-type of company.
saagarjha•9mo ago
jjmarr•9mo ago
nullpoint420•9mo ago
djmips•9mo ago
"...any compiler that is using LLVM to optimize machine code (such as the Rust compiler or clang) will not do very well for the A53, since it’s essentially trying to optimize code using a wrong CPU model. "