Re: [perf tool] cgroup support broken on Debian?

[Zefan Li <lizefan@huawei.com>]

On 2014/12/17 1:17, Vince Weaver wrote:
> On Mon, 15 Dec 2014, Stephane Eranian wrote:
>> On Mon, Dec 15, 2014 at 11:01 PM, Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com> wrote:
> 
>> fs is visible. The cgroup file system type is not there anymore. They are using
>> tmpfs which is not ideal to detect just cgroup. Looks like now, we have to look
>> at the mount point which is flaky.
> 
> The trivial fix is to just always assume things will be under
> 	/sys/fs/cgroup
> which looks like to be the new official mount point.
> 
> This will break on older systems though, or systems that mount cgroupfs in 
> multiple locations.
> 
> Another alternative is to change the interface to require the full 
> cgroupfs pathname as an argument to -G
> 

What's the problem here?

none /sys/fs/cgroup tmpfs rw,relatime,size=4k,mode=755 0 0
systemd /sys/fs/cgroup/systemd cgroup rw,nosuid,nodev,noexec,relatime,perf_event,name=systemd 0 0

cgroup is mounted in /sys/fs/cgroup/systemd, so you should pass '/' to the -G argument:

	sudo perf stat -a -e cycles:u,cycles:u,cycles:u -G / -- sleep 1