Hello, /proc/stat mounted at /var/lib/lxcfs/ is currently missing (a) the cpu average-line from the hosts /proc/stat and (b) the numbering of the cores starts with 1 and not with the 0. (This will e.g. cause confusion for top/htop in the container.) I wrote a minimally invasive patch for that:
Signed-off-by: Christian Brauner <christianvanbrau...@gmail.com>
Date: Sun Feb 15 10:34:41 2015 +0100
Bring the cpu-average line to /proc/stat mounted by lxcfs and let the
core numbering start at 0.
diff --git a/lxcfs.c b/lxcfs.c
index d6fb101..ab296e7 100644
--- a/lxcfs.c
+++ b/lxcfs.c
@@ -1642,7 +1642,7 @@ static int proc_stat_read(char *buf, size_t size, off_t
offset,
nih_local char *cpuset = NULL;
char *line = NULL;
size_t linelen = 0, total_len = 0;
- int curcpu = 0;
+ int curcpu = -1; /* cpu numbering starts at 0 */
FILE *f;
if (offset)
@@ -1662,16 +1662,22 @@ static int proc_stat_read(char *buf, size_t size, off_t
offset,
while (getline(&line, &linelen, f) != -1) {
size_t l;
int cpu;
+ char cpu_char[10]; /* That's a lot of cores */
char *c;
- if (sscanf(line, "cpu%d", &cpu) != 1) {
- /* not a ^cpu line, just print it */
+ if (sscanf(line, "cpu%9[^ ]", cpu_char) != 1) {
+ /* not a ^cpuN line containing a number N, just print it */
l = snprintf(buf, size, "%s", line);
buf += l;
size -= l;
total_len += l;
continue;
}
+ else if (sscanf(cpu_char, "%d", &cpu) != 1) {
+ }
+ else {
+ }
+
if (!cpu_in_cpuset(cpu, cpuset))
continue;
curcpu ++;
Best,
Christian
> ----- Forwarded message from Serge Hallyn <serge.hal...@ubuntu.com> -----
>
> Date: Fri, 13 Feb 2015 04:14:11 +0000
> From: Serge Hallyn <serge.hal...@ubuntu.com>
> To: Christian Brauner <christianvanbrau...@gmail.com>
> Subject: Re: cpusets in non-unified hierarchy broken?
> User-Agent: Mutt/1.5.21 (2010-09-15)
>
> Quoting Christian Brauner (christianvanbrau...@gmail.com):
> > On Thu, Feb 12, 2015 at 11:44:32PM +0000, Serge Hallyn wrote:
> > > Quoting Christian Brauner (christianvanbrau...@gmail.com):
> > > > Hi Serge,
> > > >
> > > > There is random misreporting at times from top/htop inside of the
> > > > container. Whereas e.g. cat /proc/self/status show Cpus_allowed 0-3,
> > > > top/htop will show only 1 core.
> > >
> > > It may be getting it from /proc/stat, which you *may* be getting through
> > > lxcfs. It would then be filtering it through the container's cgroup
> > > info.
> > >
> > > When you start the container, does uptime say 1 minute, or does it match
> > > the host's uptime?
> > >
> > It says uptime 0 minutes aka it does not match the host's uptime.
> > /proc/stat is looking different in the container than on the host
> > (probably because of the cgroup filtering you mentioned).
> >
> > I mentioned "random misreporting" mainly because the number of cores as
> > displayed by top/htop in the container does not match the number of cores on
> > the host. It is always less than on the host. I think this is caused by the
> > implementation of /proc/stat by lxcfs.
> >
> > E.g. on the host
> >
> > [chb@conventiont ~]$ cat /proc/stat | grep cpu
> >
> > will show
> >
> > cpu 2061 0 1623 259471 4879 0 38 0 0 0
> > cpu0 568 0 458 63949 1905 0 12 0 0 0
> > cpu1 584 0 371 65044 1018 0 8 0 0 0
> > cpu2 410 0 390 65450 786 0 12 0 0 0
> > cpu3 498 0 403 65026 1169 0 5 0 0 0
> >
> > whereas in the container
> >
> > root@vivid:~# cat /proc/stat | grep cpu
> >
> > will show
> >
> > cpu1 580 0 473 68799 1906 0 12 0 0 0
> > cpu2 600 0 384 69836 1080 0 8 0 0 0
> > cpu3 434 0 413 70268 786 0 12 0 0 0
> > cpu4 545 0 428 69839 1169 0 5 0 0 0
> >
> > So
> > (a) the cpu average-line from the hosts /proc/stat is missing.
> > and
> > (b) the numbering of the cores seems to be different in the container
> >
> > I guess this causes top/htop in the container to e.g. only show three cores
> > on
> > a four core system. Maybe, it doesn't show cpu0 at all because it thinks
> > cpu0
> > is actually cpu (average)? Lxcfs bug maybe?
>
> Seems very likely. If you have time to write a patch for that that'd be
> awesome :)
>
> (Else I'll keep it on my list)
>
> thanks,
> -serge
>
> ----- End forwarded message -----
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