On Wed, Mar 10, 2010 at 12:00:31AM +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. > > The overall design is the following: > > - account dirty pages per cgroup > - limit the number of dirty pages via memory.dirty_ratio / memory.dirty_bytes > and memory.dirty_background_ratio / memory.dirty_background_bytes in > cgroupfs > - start to write-out (background or actively) when the cgroup limits are > exceeded > > This feature is supposed to be strictly connected to any underlying IO > controller implementation, so we can stop increasing dirty pages in VM layer > and enforce a write-out before any cgroup will consume the global amount of > dirty pages defined by the /proc/sys/vm/dirty_ratio|dirty_bytes and > /proc/sys/vm/dirty_background_ratio|dirty_background_bytes limits. > Hi Andrea, I am doing a simple dd test of writting a 4G file. This machine has got 64G of memory and I have created one cgroup with 100M as limit_in_bytes. I run following dd program both in root cgroup as well as test1/ cgroup(100M limit) one after the other. In root cgroup ============== dd if=/dev/zero of=/root/zerofile bs=4K count=1000000 1000000+0 records in 1000000+0 records out 4096000000 bytes (4.1 GB) copied, 59.5571 s, 68.8 MB/s In test1/ cgroup =============== dd if=/dev/zero of=/root/zerofile bs=4K count=1000000 1000000+0 records in 1000000+0 records out 4096000000 bytes (4.1 GB) copied, 20.6683 s, 198 MB/s It is strange that we are throttling process in root group much more than process in test1/ cgroup? Thanks Vivek -- 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>