idlestat asserts if CPUs are offline at startup

[Colin Ian King]

Running idlestat on an ARM device where the CPUs are offlined when very idle idlestat asserts because pstate is NULL:

root@ubuntu-phablet:~/idlestat# ./idlestat --trace -f trace.log -t 20
...
...
warning: P-states not supported for CPU1
warning: P-states not supported for CPU2
warning: P-states not supported for CPU3
idlestat: idlestat.c:820: idlestat_load: Assertion `datas->pstates[cpu].pstate != ((void *)0)' failed.
Aborted (core dumped)

This only occurs because on startup the CPUS 1-3 are offline and hence we can't read the pstate info and so this is NULL for these cpus. During the run one or more of these CPUs pop back online, we get a trace event and the code asserts.

[Colin Ian King (colin-king)]

I get this on an x86 machine too with intel_pstate driver being used

king@lenovo:~/repos/idlestat$ sudo ./idlestat --trace -f foo -t 10
Total trace buffer: 307784 kB
failed to open '/sys/kernel/debug/tracing/events/ipi/ipi_entry/enable': No such file or directory
warning: P-states not supported for CPU0
warning: P-states not supported for CPU1
warning: P-states not supported for CPU2
warning: P-states not supported for CPU3
idlestat: idlestat.c:1026: idlestat_load: Assertion `datas->pstates[cpu].pstate != ((void *)0)' failed.

CPU: Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz