----- "Dave Anderson" <anderson@xxxxxxxxxx> wrote:
> ----- "Michael Holzheu" <holzheu@xxxxxxxxxxxxxxxxxx> wrote:
>
> > Hi Dave,
> >
> > I have a problem with a dump where I have defined five CPUs and two
> of
> > them are offline. In fact the logical CPUs are defined as follows:
> >
> > 0 on
> > 1 on
> > 2 off
> > 3 off
> > 4 on
> >
> > The CPU online map looks correct:
> >
> > crash> print/x *cpu_online_mask
> > $4 = {
> > bits = {0x13} ---> b10011
> > }
> >
> > When I issue "ps" I see that all running tasks are idle, but the CPU
> > numbers are not correct (0,1,2 and not 0,1,4):
> >
> > PID PPID CPU TASK ST %MEM VSZ RSS COMM
> > > 0 0 0 800ef0 RU 0.0 0 0 [swapper]
> > > 0 0 1 18c24240 RU 0.0 0 0 [swapper]
> > > 0 0 2 18c2c340 RU 0.0 0 0 [swapper]
> >
> > I tried to debug the problem, but got stuck somewhere in "task.c". I
> > think there is a problem with the idle threads initialization, where the
> > online map is not considered.
> >
> > Maybe you can see the bug immediately. Otherwise I will have spend more
> > effort for debugging that problem. I hope not :-)
>
> Does "sys" show 5 or 3 cpus? I'm guessing it shows 3, but should show 5.
> It looks like the s390/s390x files need to use "get_highest_cpu_online()-1"
> (like x86_64 and ppc64) in order to determine the number of cpus to account
> for. As it is now, they do this, and would therefore only account for the
> first 3 cpus:
>
> int
> s390x_get_smp_cpus(void)
> {
> return get_cpus_online();
> }
>
> int
> s390_get_smp_cpus(void)
> {
> return get_cpus_online();
> }
In other words, just have the two functions above do this:
return (get_highest_cpu_online() + 1);
The offline cpus will still show their swapper tasks and their
runqueues given that they still exist, although quiescent.
Dave
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