Launch configuration: use ZE_extension_kernel_max_group_size_properties

[maleadt]

With prime-sized inputs the suggested group size always consists of only a single thread:

julia> k = @oneapi launch=false identity(nothing)

julia> oneL0.suggest_groupsize(k.fun, 521)
oneAPI.oneL0.ZeDim3(1, 1, 1)

julia> oneL0.suggest_groupsize(k.fun, 7877)
oneAPI.oneL0.ZeDim3(1, 1, 1)

julia> oneL0.suggest_groupsize(k.fun, 7919)
oneAPI.oneL0.ZeDim3(1, 1, 1)

But also with non prime-sized inputs the configuration looks highly suboptimal:

julia> oneL0.suggest_groupsize(k.fun, 8000)
oneAPI.oneL0.ZeDim3(64, 1, 1)

(this kernel can launch groups of 512 threads on this system)

Maybe I'm misinterpreting the use of this API? I thought it was a counterpart of the CUDA occupancy API (cuOccupancyMaxPotentialBlockSize), suggesting a groupsize that accomplishes a reasonable occupancy.

[maleadt]

Filed upstream: intel/compute-runtime#725

[maleadt]

As noted by upstream, this is expected; the suggested launch configuration exactly covers the input space. Since we don't care about this, using bounds checks at run time, we can use more relaxed launch configurations. A workaround is implemented in #431, but once there's a new driver release we should use the Level Zero extension to query the maximum launch configuration for a given kernel.

[maleadt]

Fixed by #431