diff options
author | Hugh Dickins <hugh.dickins@tiscali.co.uk> | 2009-09-21 20:02:14 -0400 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-22 10:17:32 -0400 |
commit | 6e15838425ac855982f10419558649954a0684a3 (patch) | |
tree | f39e4a9b845e0bdf8f6b222ca718f155437e5b63 | |
parent | 26465d3ea5a62d59efb3796b9e0e2b0656d02cb1 (diff) |
ksm: keep quiet while list empty
ksm_scan_thread already sleeps in wait_event_interruptible until setting
ksm_run activates it; but if there's nothing on its list to look at, i.e.
nobody has yet said madvise MADV_MERGEABLE, it's a shame to be clocking
up system time and full_scans: ksmd_should_run added to check that too.
And move the mutex_lock out around it: the new counts showed that when
ksm_run is stopped, a little work often got done afterwards, because it
had been read before taking the mutex.
Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Acked-by: Izik Eidus <ieidus@redhat.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>
-rw-r--r-- | mm/ksm.c | 28 |
1 files changed, 22 insertions, 6 deletions
@@ -1280,21 +1280,27 @@ static void ksm_do_scan(unsigned int scan_npages) | |||
1280 | } | 1280 | } |
1281 | } | 1281 | } |
1282 | 1282 | ||
1283 | static int ksmd_should_run(void) | ||
1284 | { | ||
1285 | return (ksm_run & KSM_RUN_MERGE) && !list_empty(&ksm_mm_head.mm_list); | ||
1286 | } | ||
1287 | |||
1283 | static int ksm_scan_thread(void *nothing) | 1288 | static int ksm_scan_thread(void *nothing) |
1284 | { | 1289 | { |
1285 | set_user_nice(current, 5); | 1290 | set_user_nice(current, 5); |
1286 | 1291 | ||
1287 | while (!kthread_should_stop()) { | 1292 | while (!kthread_should_stop()) { |
1288 | if (ksm_run & KSM_RUN_MERGE) { | 1293 | mutex_lock(&ksm_thread_mutex); |
1289 | mutex_lock(&ksm_thread_mutex); | 1294 | if (ksmd_should_run()) |
1290 | ksm_do_scan(ksm_thread_pages_to_scan); | 1295 | ksm_do_scan(ksm_thread_pages_to_scan); |
1291 | mutex_unlock(&ksm_thread_mutex); | 1296 | mutex_unlock(&ksm_thread_mutex); |
1297 | |||
1298 | if (ksmd_should_run()) { | ||
1292 | schedule_timeout_interruptible( | 1299 | schedule_timeout_interruptible( |
1293 | msecs_to_jiffies(ksm_thread_sleep_millisecs)); | 1300 | msecs_to_jiffies(ksm_thread_sleep_millisecs)); |
1294 | } else { | 1301 | } else { |
1295 | wait_event_interruptible(ksm_thread_wait, | 1302 | wait_event_interruptible(ksm_thread_wait, |
1296 | (ksm_run & KSM_RUN_MERGE) || | 1303 | ksmd_should_run() || kthread_should_stop()); |
1297 | kthread_should_stop()); | ||
1298 | } | 1304 | } |
1299 | } | 1305 | } |
1300 | return 0; | 1306 | return 0; |
@@ -1339,10 +1345,16 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start, | |||
1339 | 1345 | ||
1340 | int __ksm_enter(struct mm_struct *mm) | 1346 | int __ksm_enter(struct mm_struct *mm) |
1341 | { | 1347 | { |
1342 | struct mm_slot *mm_slot = alloc_mm_slot(); | 1348 | struct mm_slot *mm_slot; |
1349 | int needs_wakeup; | ||
1350 | |||
1351 | mm_slot = alloc_mm_slot(); | ||
1343 | if (!mm_slot) | 1352 | if (!mm_slot) |
1344 | return -ENOMEM; | 1353 | return -ENOMEM; |
1345 | 1354 | ||
1355 | /* Check ksm_run too? Would need tighter locking */ | ||
1356 | needs_wakeup = list_empty(&ksm_mm_head.mm_list); | ||
1357 | |||
1346 | spin_lock(&ksm_mmlist_lock); | 1358 | spin_lock(&ksm_mmlist_lock); |
1347 | insert_to_mm_slots_hash(mm, mm_slot); | 1359 | insert_to_mm_slots_hash(mm, mm_slot); |
1348 | /* | 1360 | /* |
@@ -1354,6 +1366,10 @@ int __ksm_enter(struct mm_struct *mm) | |||
1354 | spin_unlock(&ksm_mmlist_lock); | 1366 | spin_unlock(&ksm_mmlist_lock); |
1355 | 1367 | ||
1356 | set_bit(MMF_VM_MERGEABLE, &mm->flags); | 1368 | set_bit(MMF_VM_MERGEABLE, &mm->flags); |
1369 | |||
1370 | if (needs_wakeup) | ||
1371 | wake_up_interruptible(&ksm_thread_wait); | ||
1372 | |||
1357 | return 0; | 1373 | return 0; |
1358 | } | 1374 | } |
1359 | 1375 | ||