Commit 4864545a authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

mm/swap: pull the CPU conditional out of __lru_add_drain_all() 

The function is too long, so pull this complicated conditional out into
cpu_needs_drain().  This ends up shrinking the text by 14 bytes,
by allowing GCC to cache the result of calling per_cpu() instead of
relocating each lookup individually.

Link: https://lkml.kernel.org/r/20220617175020.717127-11-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 82ac64d8

mm/swap.c

+16 −8
Original line number Diff line number Diff line
@@ -765,6 +765,21 @@ static void lru_add_drain_per_cpu(struct work_struct *dummy) 
	lru_add_and_bh_lrus_drain();

}



static bool cpu_needs_drain(unsigned int cpu)

{

	struct cpu_fbatches *fbatches = &per_cpu(cpu_fbatches, cpu);



	/* Check these in order of likelihood that they're not zero */

	return folio_batch_count(&fbatches->lru_add) ||

		data_race(folio_batch_count(&per_cpu(lru_rotate.fbatch, cpu))) ||

		folio_batch_count(&fbatches->lru_deactivate_file) ||

		folio_batch_count(&fbatches->lru_deactivate) ||

		folio_batch_count(&fbatches->lru_lazyfree) ||

		folio_batch_count(&fbatches->activate) ||

		need_mlock_page_drain(cpu) ||

		has_bh_in_lru(cpu, NULL);

}



/*

 * Doesn't need any cpu hotplug locking because we do rely on per-cpu

 * kworkers being shut down before our page_alloc_cpu_dead callback is
@@ -849,14 +864,7 @@ static inline void __lru_add_drain_all(bool force_all_cpus) 
	for_each_online_cpu(cpu) {

		struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);



		if (folio_batch_count(&per_cpu(cpu_fbatches.lru_add, cpu)) ||

		    data_race(folio_batch_count(&per_cpu(lru_rotate.fbatch, cpu))) ||

		    folio_batch_count(&per_cpu(cpu_fbatches.lru_deactivate_file, cpu)) ||

		    folio_batch_count(&per_cpu(cpu_fbatches.lru_deactivate, cpu)) ||

		    folio_batch_count(&per_cpu(cpu_fbatches.lru_lazyfree, cpu)) ||

		    folio_batch_count(&per_cpu(cpu_fbatches.activate, cpu)) ||

		    need_mlock_page_drain(cpu) ||

		    has_bh_in_lru(cpu, NULL)) {

		if (cpu_needs_drain(cpu)) {

			INIT_WORK(work, lru_add_drain_per_cpu);

			queue_work_on(cpu, mm_percpu_wq, work);

			__cpumask_set_cpu(cpu, &has_work);