Re: [PATCH] sched/fair: optimize should_we_balance for higher SMT systems

[Tim Chen]

On Wed, 2023-09-06 at 07:36 +0530, Shrikanth Hegde wrote:
> 
> Hi Tim,
> 
> Thanks for taking a look at this patch.
> 
> > Wonder if we can avoid allocating the 
> > should_we_balance_tmpmask for SMT2 case to save memory
> > for system with large number of cores.
> > 
> > The new mask and logic I think is only needed for more than 2 threads in a core.
> 
> Code would have to be refactored quite a bit if one needs to take
> different approach for specific SMT setting. 
> 
> I think there would some cases in SMT2 that will benefit as well. 
> Lets say 1 cpu in each core is busy. the busy CPU happens to be second 
> CPU in the core. In that case, this approach would skip that instead of 
> checking if that is idle or not. 
> 
> 
That's true. This change could skip the sibling for SMT2.

Tim