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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: David Rientjes <rientjes@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Rientjes 2016-05-20 16:58:56 -07:00 committed by Linus Torvalds
parent a53eaff8c1
commit f050897778
1 changed files with 16 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
mm/huge_memory.c
View File

@ -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;
}