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Commit f000565a authored by Andrea Arcangeli's avatar Andrea Arcangeli Committed by Linus Torvalds
Browse files

thp: set recommended min free kbytes 



If transparent hugepage is enabled initialize min_free_kbytes to an
optimal value by default.  This moves the hugeadm algorithm in kernel.

Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent cd7548ab

mm/huge_memory.c

+52 −0
Original line number Diff line number Diff line
@@ -85,6 +85,47 @@ struct khugepaged_scan { 
	.mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),

};





static int set_recommended_min_free_kbytes(void)

{

	struct zone *zone;

	int nr_zones = 0;

	unsigned long recommended_min;

	extern int min_free_kbytes;



	if (!test_bit(TRANSPARENT_HUGEPAGE_FLAG,

		      &transparent_hugepage_flags) &&

	    !test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,

		      &transparent_hugepage_flags))

		return 0;



	for_each_populated_zone(zone)

		nr_zones++;



	/* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */

	recommended_min = pageblock_nr_pages * nr_zones * 2;



	/*

	 * Make sure that on average at least two pageblocks are almost free

	 * of another type, one for a migratetype to fall back to and a

	 * second to avoid subsequent fallbacks of other types There are 3

	 * MIGRATE_TYPES we care about.

	 */

	recommended_min += pageblock_nr_pages * nr_zones *

			   MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;



	/* don't ever allow to reserve more than 5% of the lowmem */

	recommended_min = min(recommended_min,

			      (unsigned long) nr_free_buffer_pages() / 20);

	recommended_min <<= (PAGE_SHIFT-10);



	if (recommended_min > min_free_kbytes)

		min_free_kbytes = recommended_min;

	setup_per_zone_wmarks();

	return 0;

}

late_initcall(set_recommended_min_free_kbytes);



static int start_khugepaged(void)

{

	int err = 0;
@@ -108,6 +149,8 @@ static int start_khugepaged(void) 
		mutex_unlock(&khugepaged_mutex);

		if (wakeup)

			wake_up_interruptible(&khugepaged_wait);



		set_recommended_min_free_kbytes();

	} else

		/* wakeup to exit */

		wake_up_interruptible(&khugepaged_wait);
@@ -177,6 +220,13 @@ static ssize_t enabled_store(struct kobject *kobj, 
			ret = err;

	}



	if (ret > 0 &&

	    (test_bit(TRANSPARENT_HUGEPAGE_FLAG,

		      &transparent_hugepage_flags) ||

	     test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,

		      &transparent_hugepage_flags)))

		set_recommended_min_free_kbytes();



	return ret;

}

static struct kobj_attribute enabled_attr =
@@ -464,6 +514,8 @@ static int __init hugepage_init(void) 


	start_khugepaged();



	set_recommended_min_free_kbytes();



out:

	return err;

}