Re: [PATCH 2/3] powerpc: Instrument Hypervisor Calls: add wrappers

Paul Mackerras wrote:

Nathan Lynch writes:

quoted

Without disabling preemption around the mfspr ... update_stats section
in these hcall wrappers, you risk updating the stats on the wrong cpu.

I think we are only looking for total counts and times anyway, so it
doesn't really matter which cpu updates the stats, as long as the time
gets accounted on some cpu.  The use of per-cpu counters is just for
better cache behaviour.

Makes sense... then perhaps the stats shouldn't be exported in per-cpu
files in sysfs, and the kernel should calculate and report the totals
to userspace in some other form.