Treat return code -1 as error instead.
People from glibc say that errno is undefined in case of successful
sysconf call according to POSIX standard:
Glibc bug: https://sourceware.org/bugzilla/show_bug.cgi?id=21536
More over in sysconf man it is wrongly said that "errno is not changed"
on success. So I've created a bug to man-pages:
https://bugzilla.kernel.org/show_bug.cgi?id=195955
Background: Glibc's sysconf(_SC_NPROCESSORS_ONLN) changes errno to
ENOENT, if there is no /sys/devices/system/cpu/online file, while
the call itself is successful. In Virtuozzo containers we prohibit
most of sysfs files for security reasons. So we have Run():daemon
/stats/collector.go infinitely loop never actualy collecting stats
from publisher pairs.
v2: add comment
Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
In https://github.com/torvalds/linux/commit/5ca3726 (released in v4.7-rc1) the
content of the `cpuacct.usage_percpu` file in sysfs was changed to include both
online and offline cpus. This broke the arithmetic in the stats helpers used by
`docker stats`, since it was using the length of the PerCPUUsage array as a
proxy for the number of online CPUs.
Add current number of online CPUs to types.StatsJSON and use it in the
calculation.
Keep a fallback to `len(v.CPUStats.CPUUsage.PercpuUsage)` so this code
continues to work when talking to an older daemon. An old client talking to a
new daemon will ignore the new field and behave as before.
Fixes#28941.
Signed-off-by: Ian Campbell <ian.campbell@docker.com>
