Re: [PATCH 2/2] x86/hpet: use an atomic add instead of a cmpxchg loop

[Julien Grall <julien@xxxxxxx>]

Hi Roger,

On 22/02/2024 09:05, Roger Pau Monne wrote:
> The usage of a cmpxchg loop in hpet_get_channel() is unnecessary, as the same
> can be achieved with an atomic increment, which is both simpler to read, and
> avoid any need for a loop.
>
> Note there can be a small divergence in the channel returned if next_channel
> overflows, but returned channel will always be in the [0, num_hpets_used)
> range, and that's fine for the purpose of balancing HPET channels across CPUs.
> This is also theoretical, as there's no system currently with 2^32 CPUs (as
> long as next_channel is 32bit width).
This would also happen if we decide to reduce the size next_channel.

Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx>

Cheers,

--
Julien Grall