Re: [PATCH v4 2/2] arm64: support batched/deferred tlb shootdown during page reclamation

[Anshuman Khandual]

[...]

On 9/21/22 14:13, Yicong Yang wrote:
> +static inline bool arch_tlbbatch_should_defer(struct mm_struct *mm)
> +{
> +	/* for small systems with small number of CPUs, TLB shootdown is cheap */
> +	if (num_online_cpus() <= 4)

It would be great to have some more inputs from others, whether 4 (which should
to be codified into a macro e.g ARM64_NR_CPU_DEFERRED_TLB, or something similar)
is optimal for an wide range of arm64 platforms.

> +		return false;> +
> +#ifdef CONFIG_ARM64_WORKAROUND_REPEAT_TLBI
> +	if (unlikely(this_cpu_has_cap(ARM64_WORKAROUND_REPEAT_TLBI)))
> +		return false;
> +#endif
> +
> +	return true;
> +}
> +

[...]