Re: [PATCH v2 2/5] Introducing qpw_lock() and per-cpu queue & flush work

[Vlastimil Babka (SUSE)]

On 3/2/26 16:49, Marcelo Tosatti wrote:
> +#define local_qpw_lock(lock)								\
> +	do {										\
> +		if (static_branch_maybe(CONFIG_QPW_DEFAULT, &qpw_sl)) {			\
> +			migrate_disable();						\

Have you considered using migrate_disable() on PREEMPT_RT and
preempt_disable() on !PREEMPT_RT since it's cheaper? It's what the pcp
locking in mm/page_alloc.c does, for that reason. It should reduce the
overhead with qpw=1 on !PREEMPT_RT.

> +			spin_lock(this_cpu_ptr(lock.sl));				\
> +		} else									\
> +			local_lock(lock.ll);						\
> +	} while (0)
> +