* Vivek Goyal <vgoyal@xxxxxxxxxx> [2010-03-15 13:19:21]: > On Mon, Mar 15, 2010 at 01:12:09PM -0400, Vivek Goyal wrote: > > On Mon, Mar 15, 2010 at 12:26:37AM +0100, Andrea Righi wrote: > > > Control the maximum amount of dirty pages a cgroup can have at any given time. > > > > > > Per cgroup dirty limit is like fixing the max amount of dirty (hard to reclaim) > > > page cache used by any cgroup. So, in case of multiple cgroup writers, they > > > will not be able to consume more than their designated share of dirty pages and > > > will be forced to perform write-out if they cross that limit. > > > > > > > For me even with this version I see that group with 100M limit is getting > > much more BW. > > > > root cgroup > > ========== > > #time dd if=/dev/zero of=/root/zerofile bs=4K count=1M > > 4294967296 bytes (4.3 GB) copied, 55.7979 s, 77.0 MB/s > > > > real 0m56.209s > > > > test1 cgroup with memory limit of 100M > > ====================================== > > # time dd if=/dev/zero of=/root/zerofile1 bs=4K count=1M > > 4294967296 bytes (4.3 GB) copied, 20.9252 s, 205 MB/s > > > > real 0m21.096s > > > > Note, these two jobs are not running in parallel. These are running one > > after the other. > > > > Ok, here is the strange part. I am seeing similar behavior even without > your patches applied. > > root cgroup > ========== > #time dd if=/dev/zero of=/root/zerofile bs=4K count=1M > 4294967296 bytes (4.3 GB) copied, 56.098 s, 76.6 MB/s > > real 0m56.614s > > test1 cgroup with memory limit 100M > =================================== > # time dd if=/dev/zero of=/root/zerofile1 bs=4K count=1M > 4294967296 bytes (4.3 GB) copied, 19.8097 s, 217 MB/s > > real 0m19.992s > This is strange, did you flish the cache between the two runs? NOTE: Since the files are same, we reuse page cache from the other cgroup. -- Three Cheers, Balbir -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>