Stephane Eranian wrote:
> This kernel patch adds the ability to filter monitoring based on
> container groups (cgroups). This is for use in per-cpu mode only.
>
> The cgroup to monitor is passed as a file descriptor in the pid
> argument to the syscall. The file descriptor must be opened to
> the cgroup name in the cgroup filesystem. For instance, if the
> cgroup name is foo and cgroupfs is mounted in /cgroup, then the
> file descriptor is opened to /cgroup/foo. Cgroup mode is
> activated by passing PERF_FLAG_PID_CGROUP in the flags argument
> to the syscall.
>
> For instance to measure in cgroup foo on CPU1 assuming
> cgroupfs is mounted under /cgroup:
>
> struct perf_event_attr attr;
> int cgroup_fd, fd;
>
> cgroup_fd = open("/cgroup/foo", O_RDONLY);
> fd = perf_event_open(&attr, cgroup_fd, 1, -1, PERF_FLAG_PID_CGROUP);
> close(cgroup_fd);
>
> Signed-off-by: Stephane Eranian <eran...@google.com>
For the cgroup part:
Acked-by: Li Zefan <l...@cn.fujitsu.com>
a few comments below:
>
...
> +config CGROUP_PERF
> + bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
> + depends on PERF_EVENTS && CGROUPS
Depending on CGROUPS is already implicated by "if CGROUPS"
> + help
> + This option extends the per-cpu mode to restrict monitoring to
> + threads which belong to the cgroup specificied and run on the
> + designated cpu.
> +
> + Say N if unsure.
> +
> menuconfig CGROUP_SCHED
> bool "Group CPU scheduler"
> depends on EXPERIMENTAL
...
> +static inline int perf_cgroup_connect(int fd, struct perf_event *event,
> + struct perf_event_attr *attr,
> + struct perf_event *group_leader)
> +{
> + struct perf_cgroup *cgrp;
> + struct cgroup_subsys_state *css;
> + struct file *file;
> + int ret = 0, fput_needed;
> +
> + file = fget_light(fd, &fput_needed);
> + if (!file)
> + return -EBADF;
> +
> + css = cgroup_css_from_dir(file, perf_subsys_id);
> + if (IS_ERR(css))
> + return PTR_ERR(css);
> +
> + cgrp = container_of(css, struct perf_cgroup, css);
> + event->cgrp = cgrp;
> +
> + /*
> + * all events in a group must monitor
> + * the same cgroup because a thread belongs
> + * to only one perf cgroup at a time
> + */
> + if (group_leader && group_leader->cgrp != cgrp) {
> + perf_detach_cgroup(event);
This doesn't seem right, because we haven't got the cgroup
refcount.
> + ret = -EINVAL;
> + } else {
> + /* must be done before we fput() the file */
> + perf_get_cgroup(event);
> + }
> + fput_light(file, fput_needed);
> + return ret;
> +}
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