Commit f0508977 authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds
Browse files

mm, thp: khugepaged should scan when sleep value is written 

If a large value is written to scan_sleep_millisecs, for example, that
period must lapse before khugepaged will wake up for periodic
collapsing.

If this value is tuned to 1 day, for example, and then re-tuned to its
default 10s, khugepaged will still wait for a day before scanning again.

This patch causes khugepaged to wakeup immediately when the value is
changed and then sleep until that value is rewritten or the new value
lapses.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1605181453200.4786@chino.kir.corp.google.com


Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea 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 a53eaff8

mm/huge_memory.c

+16 −3
Original line number Diff line number Diff line
@@ -89,6 +89,7 @@ static unsigned int khugepaged_full_scans; 
static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;

/* during fragmentation poll the hugepage allocator once every minute */

static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;

static unsigned long khugepaged_sleep_expire;

static struct task_struct *khugepaged_thread __read_mostly;

static DEFINE_MUTEX(khugepaged_mutex);

static DEFINE_SPINLOCK(khugepaged_mm_lock);
@@ -467,6 +468,7 @@ static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, 
		return -EINVAL;



	khugepaged_scan_sleep_millisecs = msecs;

	khugepaged_sleep_expire = 0;

	wake_up_interruptible(&khugepaged_wait);



	return count;
@@ -494,6 +496,7 @@ static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, 
		return -EINVAL;



	khugepaged_alloc_sleep_millisecs = msecs;

	khugepaged_sleep_expire = 0;

	wake_up_interruptible(&khugepaged_wait);



	return count;
@@ -2791,15 +2794,25 @@ static void khugepaged_do_scan(void) 
		put_page(hpage);

}



static bool khugepaged_should_wakeup(void)

{

	return kthread_should_stop() ||

	       time_after_eq(jiffies, khugepaged_sleep_expire);

}



static void khugepaged_wait_work(void)

{

	if (khugepaged_has_work()) {

		if (!khugepaged_scan_sleep_millisecs)

		const unsigned long scan_sleep_jiffies =

			msecs_to_jiffies(khugepaged_scan_sleep_millisecs);



		if (!scan_sleep_jiffies)

			return;



		khugepaged_sleep_expire = jiffies + scan_sleep_jiffies;

		wait_event_freezable_timeout(khugepaged_wait,

					     kthread_should_stop(),

			msecs_to_jiffies(khugepaged_scan_sleep_millisecs));

					     khugepaged_should_wakeup(),

					     scan_sleep_jiffies);

		return;

	}

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