Em Mon, Dec 15, 2014 at 04:07:46PM -0500, Vince Weaver escreveu: > Hello > > has anyone tested the perf tool cgroup support recently? > > I was trying to get it working with a command like > sudo perf stat -a -e cycles:u,cycles:u,cycles:u -G systemd -- sleep 1 > > and it just failed by unhelfully dumping the "-G" help text. > Once I added a lot of extra debug printfs to tools/perf/util/cgroup.c > things became a little clearer. > > First, you apparently need "perf_event" passed as a mount option to the > cgroup or you cannot attach perf to it (should perf be modified to > print a warning in this case rather than just printing the unhelpful > helf text?)
yes, please > Secondly, the cgroup mount point detection completely fails on my debian > box. On my machine /proc/mounts has this: > > ... > 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 > > The current perf code looks for "cgroup" in the type field to find the > root cgroupfs tree. This fails because as seen above on my machine the > cgroup mount has type tmpfs. And when it finds > /sys/fs/cgroup/systemd as the root it tacks the name onto the end > (/sys/fs/cgroup/systemd/systemd) which obviously doesn't exist. > > Once I hack the code to avoid that I do finally get some cgroup readings. > > I was checking if this was a known problem, a Debian issue, or what... Its just that the cgroup support is rough, patches are welcome to improve the situation. BTW, here its fedora20, same problem: [root@zoo ~]# mount | grep cgroup tmpfs on /sys/fs/cgroup type tmpfs (rw,nosuid,nodev,noexec,seclabel,mode=755) cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd) - Arnaldo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/