Delete Device2Host caused by comm with device and host

[zhaozheng09]

Delete some D2H ops

if not will be bring a sync within host and device, so replace it from if not to torch.where

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before:

after:

Host will be block until device done, this D2H maybe block pipeline of host and device, so I use where op to replace if not

[Borda]

can we pls add tests for this fix?
and maybe pls update the title to better express what the PR does

[codecov]

Codecov Report

Attention: Patch coverage is 90.90909% with 2 lines in your changes missing coverage. Please review.

Project coverage is 69%. Comparing base (b9ab4bc) to head (6ced9ed).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #2840    +/-   ##
=======================================
- Coverage      69%     69%    -0%     
=======================================
  Files         346     332    -14     
  Lines       19130   18957   -173     
=======================================
- Hits        13228   13054   -174     
- Misses       5902    5903     +1     

[zhaozheng09]

can we pls add tests for this fix? and maybe pls update the title to better express what the PR does

must be 100% cover ? this code will raise in old torch version, I don't know how to cover, please give me an example ? thx very much.

[Borda]

this code will raise in old torch version, I don't know how to cover, please give me an example ? thx very much

ok, so you say that this PR does not have any impact on functional metrics results but improves performances, correct?

[SkafteNicki]

did a couple of changes to the PR:

• move the logic torch.where logic to a separate function such that it could be used multiple places
• made the testing of cpu+sigmoid+half less restrictive e.g. instead of always being skipped it is now only skipped for older pytorch builds

[lantiga]

Looks good, thanks!

In general we will have to become sensitive to data-dependent control flow, to make torchmetrics more compiler-friendly in the future. This applies to both before and after this PR of course, having the condition in a separate function like it is now allows us to side-step the problem, so the final state is better from this point of view.