| From | Luis Henriques <> | Subject | [PATCH 3.16.y-ckt 109/254] dm bufio: update last_accessed when relinking a buffer | Date | Tue, 25 Nov 2014 10:37:39 +0000 |
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3.16.7-ckt2 -stable review patch. If anyone has any objections, please let me know.
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From: Joe Thornber <ejt@redhat.com>
commit eb76faf53b1ff7a77ce3f78cc98ad392ac70c2a0 upstream.
The 'last_accessed' member of the dm_buffer structure was only set when the the buffer was created. This led to each buffer being discarded after dm_bufio_max_age time even if it was used recently. In practice this resulted in all thinp metadata being evicted soon after being read -- this is particularly problematic for metadata intensive workloads like multithreaded small random IO.
'last_accessed' is now updated each time the buffer is moved to the head of the LRU list, so the buffer is now properly discarded if it was not used in dm_bufio_max_age time.
Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/md/dm-bufio.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c index d724459860d9..da2ebac231b9 100644 --- a/drivers/md/dm-bufio.c +++ b/drivers/md/dm-bufio.c @@ -465,6 +465,7 @@ static void __relink_lru(struct dm_buffer *b, int dirty) c->n_buffers[dirty]++; b->list_mode = dirty; list_move(&b->lru_list, &c->lru[dirty]); + b->last_accessed = jiffies; } /*---------------------------------------------------------------- -- 2.1.0
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