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SubjectRe: Attaching a process to cgroups
On Wed, Jul 25, 2012 at 03:57:47PM +0200, Mike Galbraith wrote:
>
> I'd profile it with perf, and expect to find a large pile of cycles.

I did it the as following:
# perf stat cat /proc/self/cgroup

4:blkio:/
3:devices:/
2:memory:/
1:cpuacct:/

Performance counter stats for 'cat /proc/self/cgroup':

0.472513 task-clock # 0.000 CPUs utilized
1 context-switches # 0.002 M/sec
1 CPU-migrations # 0.002 M/sec
169 page-faults # 0.358 M/sec
1111521 cycles # 2.352 GHz
784737 stalled-cycles-frontend # 70.60% frontend cycles idle
445520 stalled-cycles-backend # 40.08% backend cycles idle
576622 instructions # 0.52 insns per cycle
# 1.36 stalled cycles per insn
120032 branches # 254.029 M/sec
6577 branch-misses # 5.48% of all branches

9.114631804 seconds time elapsed

# perf report --sort comm,dso
Kernel address maps (/proc/{kallsyms,modules}) were restricted.

Check /proc/sys/kernel/kptr_restrict before running 'perf record'.

If some relocation was applied (e.g. kexec) symbols may be misresolved.

Samples in kernel modules can't be resolved as well.

# ========
# captured on: Thu Jul 26 16:23:06 2012
# hostname : l24
# os release : 3.3.3-1gb-c-s-m
# perf version : 3.2
# arch : x86_64
# nrcpus online : 24
# nrcpus avail : 24
# cpudesc : Intel(R) Xeon(R) CPU E5645 @ 2.40GHz
# total memory : 74181032 kB
# cmdline : /usr/sbin/perf record cat /proc/self/cgroup
# event : name = cycles, type = 0, config = 0x0, config1 = 0x0, config2 = 0x0, excl_usr = 0, excl_kern = 0, id = { 1758, 1759, 1760, 1761, 1762, 1763, 1764, 1765, 1766, 1767, 1768, 1769, 1770, 1771, 1772, 1773, 1774, 1775, 1776, 1777, 1778, 1779, 1780, 1781 }
# HEADER_CPU_TOPOLOGY info available, use -I to display
# HEADER_NUMA_TOPOLOGY info available, use -I to display
# ========
#
# Events: 21 cycles
#
# Overhead Command Shared Object
# ........ ....... .................
#
100.00% cat [kernel.kallsyms]

but I don't know what next unfortunately.

I also checked the same thing on the other server with the 2.6.37 kernel,
there' some thousands cgroups too, and it somehow works there immediately.

--
Alexey Vlasov


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