v4.1.x: coll/ucc: add reduce scatter block

[Sergei-Lebedev]

Adding reduce scatter block to ucc coll component

Signed-off-by: Sergey Lebedev sergeyle@nvidia.com bot:notacherrypick

[jsquyres]

@Sergei-Lebedev Is there a reason to add this to v4.1.x? The v4.1.x series is closing down -- we really don't want to accept new features. Instead, the goal should be to get new things into main + v5.0.x.

[Sergei-Lebedev]

@Sergei-Lebedev Is there a reason to add this to v4.1.x? The v4.1.x series is closing down -- we really don't want to accept new features. Instead, the goal should be to get new things into main + v5.0.x.

coll ucc already has reduce scatter block in v5.0.x, but in HPCX we are still using v4.1.x. Maybe @janjust can add more details.

[janjust]

This is the only reason, we want to move onto v5.0.x but are not ready yet and HPC-X will ship with v4.1.x for at least another release cycle. And as far as I know same is true for HPC-SDK, they're still on v4.1.x

[jsquyres]

Ok. This is entirely within your component, so... so be it.

But please move to v5.0.x as soon as you can. 😈

[jsquyres]

bot:ompi:retest

[janjust]

Thank you 🙏