On Sun, Oct 03, 2010 at 11:57:55PM -0700, Greg Thelen wrote: > This patch set provides the ability for each cgroup to have independent dirty > page limits. > > Limiting dirty memory is like fixing the max amount of dirty (hard to reclaim) > page cache used by a 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. > > These patches were developed and tested on mmotm 2010-09-28-16-13. The patches > are based on a series proposed by Andrea Righi in Mar 2010. > > Overview: > - Add page_cgroup flags to record when pages are dirty, in writeback, or nfs > unstable. > - Extend mem_cgroup to record the total number of pages in each of the > interesting dirty states (dirty, writeback, unstable_nfs). > - Add dirty parameters similar to the system-wide /proc/sys/vm/dirty_* > limits to mem_cgroup. The mem_cgroup dirty parameters are accessible > via cgroupfs control files. > - Consider both system and per-memcg dirty limits in page writeback when > deciding to queue background writeback or block for foreground writeback. > > Known shortcomings: > - When a cgroup dirty limit is exceeded, then bdi writeback is employed to > writeback dirty inodes. Bdi writeback considers inodes from any cgroup, not > just inodes contributing dirty pages to the cgroup exceeding its limit. > > Performance measurements: > - kernel builds are unaffected unless run with a small dirty limit. > - all data collected with CONFIG_CGROUP_MEM_RES_CTLR=y. > - dd has three data points (in secs) for three data sizes (100M, 200M, and 1G). > As expected, dd slows when it exceed its cgroup dirty limit. > > kernel_build dd > mmotm 2:37 0.18, 0.38, 1.65 > root_memcg > > mmotm 2:37 0.18, 0.35, 1.66 > non-root_memcg > > mmotm+patches 2:37 0.18, 0.35, 1.68 > root_memcg > > mmotm+patches 2:37 0.19, 0.35, 1.69 > non-root_memcg > > mmotm+patches 2:37 0.19, 2.34, 22.82 > non-root_memcg > 150 MiB memcg dirty limit > > mmotm+patches 3:58 1.71, 3.38, 17.33 > non-root_memcg > 1 MiB memcg dirty limit Hi Greg, the patchset seems to work fine on my box. I also ran a pretty simple test to directly verify the effectiveness of the dirty memory limit, using a dd running on a non-root memcg: dd if=/dev/zero of=tmpfile bs=1M count=512 and monitoring the max of the "dirty" value in cgroup/memory.stat: Here the results: dd in non-root memcg ( 4 MiB memcg dirty limit): dirty max=4227072 dd in non-root memcg ( 8 MiB memcg dirty limit): dirty max=8454144 dd in non-root memcg ( 16 MiB memcg dirty limit): dirty max=15179776 dd in non-root memcg ( 32 MiB memcg dirty limit): dirty max=32235520 dd in non-root memcg ( 64 MiB memcg dirty limit): dirty max=64245760 dd in non-root memcg (128 MiB memcg dirty limit): dirty max=121028608 dd in non-root memcg (256 MiB memcg dirty limit): dirty max=232865792 dd in non-root memcg (512 MiB memcg dirty limit): dirty max=445194240 -Andrea -- 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>