Re: [PATCH 13/21] x86/intel_rdt/cqm: Add cpus file support

From: Thomas Gleixner
Date: Sun Jul 02 2017 - 07:12:23 EST

On Mon, 26 Jun 2017, Vikas Shivappa wrote:
> diff --git a/arch/x86/kernel/cpu/intel_rdt.h b/arch/x86/kernel/cpu/intel_rdt.h
> index fdf3654..fec8ba9 100644
> --- a/arch/x86/kernel/cpu/intel_rdt.h
> +++ b/arch/x86/kernel/cpu/intel_rdt.h
> @@ -37,6 +37,8 @@ struct mon_evt {
> extern bool rdt_alloc_enabled;
> extern int rdt_mon_features;
> +DECLARE_PER_CPU_READ_MOSTLY(int, cpu_rmid);


> +DEFINE_PER_CPU_READ_MOSTLY(int, cpu_rmid);
> static inline struct rmid_entry *__rmid_entry(u32 rmid)

Bah. Please add a new line between the DEFINE... and the function.

But that whole thing is wrong. The per cpu default closid and rmid want to
be in a single place, not in two distinct per cpu variables.

struct rdt_cpu_default {
u32 rmid;
u32 closid;

DEFINE_PER_CPU_READ_MOSTLY(struct rdt_cpu_default, rdt_cpu_default);

or something like this. That way it's guaranteed that the context switch
code touches a single cache line for the per cpu defaults.