Re: [PATCH v10 09/12] x86/mm: enable broadcast TLB invalidation for multi-threaded processes

[Nadav Amit]

It all looks pretty sane to me.

One small note:

> On 11 Feb 2025, at 23:08, Rik van Riel <riel@xxxxxxxxxxx> wrote:
> 
> +/*
> + * Check whether a process is currently active on more than "threshold" CPUs.
> + * This is a cheap estimation on whether or not it may make sense to assign
> + * a global ASID to this process, and use broadcast TLB invalidation.
> + */
> +static bool mm_active_cpus_exceeds(struct mm_struct *mm, int threshold)
> +{
> +	int count = 0;
> +	int cpu;
> +
> +	/* This quick check should eliminate most single threaded programs. */
> +	if (cpumask_weight(mm_cpumask(mm)) <= threshold)
> +		return false;
> +

Does it make sense to first check mm.mm_users against the threshold? It might
be less cache-contended.

Anyhow, for what’s it worth:

Reviewed-by: Nadav Amit <nadav.amit@xxxxxxxxx <mailto:nadav.amit@xxxxxxxxx>>