Added description about pids count.
Documentation in response to issue docker/for-linux#192
@@ -36,6 +36,8 @@ If you want more detailed information about a container's resource usage, use th
> **Note**: On Linux, the Docker CLI reports memory usage by subtracting page cache usage from the total memory usage. The API does not perform such a calculation but rather provides the total memory usage and the amount from the page cache so that clients can use the data as needed.
+> **Note**: The `PIDS` column contains the number of processes and kernel threads created by that container. Threads is the term used by Linux kernel. Other equivalent terms are "lightweight process" or "kernel task", etc. A large number in the `PIDS` column combined with a small number of processes (as reported by `ps` or `top`) may indicate that something in the container is creating many threads.
+
## Examples
Running `docker stats` on all running containers against a Linux daemon.
