I thank Guido Jäkel for raising the issue cited in the
merge request referenced below. While restoring 1 line
of code would produce the desired results, it does not
address the root cause of that problem he experienced.
The variable 'smp_num_cpus' was set by libprocps via a
sysconf(_SC_NPROCESSORS_ONLN) call. It was supposed to
represent total number of processors currently online.
It also served as the position in the Cpu_tics[] array
where the /proc/stat line #1 (cpu summary) was stored.
The variable 'Cpu_faux_tot' was valued by top based on
total individual cpus parsed from the /proc/stat file.
It serves as a fence post for Cpu_tics[] array access.
The problem Guido experienced results from a disparity
between those 2 variables, plus one instance where the
wrong variable was used in the summary_show() routine.
. Here is the real culprit, the actual incorrect code:
. summary_hlp(&Cpu_tics[Cpu_faux_tot], N_txt(WORD_a...
Which always should have been represented in this way:
. summary_hlp(&Cpu_tics[smp_num_cpus], N_txt(WORD_a...
------------------------------------------------------
The above 'disparity' might arise in any system when a
cpu is taken offline since there's a 3 second delay in
cpu and memory refreshes in an effort to reduce costs.
Usually this particular condition will be short lived.
However, there is a more persistent problem under lxc.
If a host cpu is taken offline and then brought online
again, within the container sysconf returns the proper
number of online processors. But, /proc/stat does not!
Sadly, I've yet to find a way to coax a container into
refreshing its /proc/stat, short of reboting the host.
[ might that represent a potential bug in lxc logic? ]
projects / procps-ng / commit