I have a Java application running in Ubuntu 14.04 container. The application relies OS pagecache to speed-up reads and writes. The container is issued a pause command which according to docker documentation triggers a cgroup freezer https://www.kernel.org/doc/Documentation/cgroups/freezer-subsystem.txt.
What happens to dirty pages and pagecache of the paused container? Are they flushed to disk? Or the whole notion of container-scope pagecache is wrong and dirty pages for all containers are managed at the docker host level?
docker host free -m:
user@0000 ~ # free -m
total used free shared buffers cached
Mem: 48295 47026 1269 0 22 45010
-/+ buffers/cache: 1993 46302
Swap: 24559 12 24547
container docker exec f1b free -m
user@0000 ~ # docker exec f1b free -m
total used free shared buffers
Mem: 48295 47035 1259 0 22
-/+ buffers: 47013 1282
Swap: 24559 12 24547
Once a container is paused, I cannot check memory as seen by the container.
FATA[0000] Error response from daemon: Container f1 is paused, unpause the container before exec