On Tue, Feb 28, 2012 at 11:00 AM, Glauber Costa <glommer@xxxxxxxxxxxxx> wrote: > On 02/27/2012 07:58 PM, Suleiman Souhlal wrote: >> >> A later patch will also use this to move the accounting to the root >> cgroup. >> > > Suleiman, > > Did you do any measurements to figure out how long does it take, average, > for dangling caches to go away ? Under memory pressure, let's say Unfortunately, I don't have any such measurements, other than a very artificial: # mkdir /dev/cgroup/memory/c # echo 1073741824 > /dev/cgroup/memory/c/memory.limit_in_bytes # sync && echo 3 > /proc/sys/vm/drop_caches # echo $$ > /dev/cgroup/memory/c/tasks # find / > /dev/null # grep '(c)' /proc/slabinfo | wc -l 42 # echo $$ > /dev/cgroup/memory/tasks # rmdir /dev/cgroup/memory/c # grep '(c)dead' /proc/slabinfo | wc -l 42 # sleep 60 && sync && for i in `seq 1 1000`; do echo 3 > /proc/sys/vm/drop_caches ; done # grep '(c)dead' /proc/slabinfo | wc -l 6 # sleep 60 && grep '(c)dead' /proc/slabinfo | wc -l 5 # sleep 60 && grep '(c)dead' /proc/slabinfo | wc -l 5 (Note that this is without any per-memcg shrinking patch applied. With shrinking, things will be a bit better, because deleting the cgroup will force the dentries to get shrunk.) Some of these dead caches may take a long time to go away, but we haven't found them to be a problem for us, so far. -- Suleiman -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>