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SubjectRe: [PATCH 01/10] x86_64: Cleanup non-smp usage of cpu maps v2
Ingo Molnar wrote:
> * Mike Travis <travis@sgi.com> wrote:
>
>> Cleanup references to the early cpu maps for the non-SMP configuration
>> and remove some functions called for SMP configurations only.
>
> thanks, applied.
>
> one observation:
>
>> +#ifdef CONFIG_SMP
>> extern int x86_cpu_to_node_map_init[];
>> extern void *x86_cpu_to_node_map_early_ptr;
>> +#else
>> +#define x86_cpu_to_node_map_early_ptr NULL
>> +#endif
>
> Right now all these early_ptrs are in essence open-coded "early
> per-cpu", right? But shouldnt we solve that in a much cleaner way: by
> explicitly adding an early-per-cpu types and accessors, and avoid all
> that #ifdeffery?
>
> Ingo

How about something like the below? (I haven't tried compiling it yet.)

[I also thought about not restricting it to only NR_CPUS type variables
to allow for example, node-local node maps/variables.]

Thanks,
Mike
------------------------------------------------------------
include/linux/percpu.h:
#ifdef CONFIG_SMP
#define DEFINE_EARLY_PER_CPU(type, name, initvalue) \
DEFINE_PER_CPU(type, name) = initvalue; \
type name##_early_map[NR_CPUS] __initdata = \
{ [0 ... NR_CPUS-1] = initvalue; } \
type *name##_early_ptr = name##_early_map
#define DECLARE_EARLY_PER_CPU(type, name) \
DECLARE_PER_CPU(type, name); \
extern type *name##_early_ptr; \
extern type name##_early_map[]

#define EXPORT_EARLY_PER_CPU(name) \
EXPORT_PER_CPU(name)

/* rvalue only */
#define early_per_cpu(name, cpu) \
(name##ptr? name##ptr[cpu] : per_cpu(name, cpu))
#define early_per_cpu_ptr(name) (name##_early_ptr)
#define early_per_cpu_map(name, idx) (name##_early_map[idx])
#else /* !CONFIG_SMP */
#define DEFINE_EARLY_PER_CPU(type, name, initvalue) \
DEFINE_PER_CPU(type, name) = initvalue
#define DECLARE_EARLY_PER_CPU(name) \
DECLARE_PER_CPU(name)

#define EXPORT_EARLY_PER_CPU(name) \
EXPORT_PER_CPU(name)

#define early_per_cpu(name, cpu) per_cpu(name, cpu)
#define early_per_cpu_ptr(name) NULL
/* no early_per_cpu_map() */
#endif /* !CONFIG_SMP */

------------------------------------------------------------
include/asm-x86/smp.h:
DECLARE_EARLY_PER_CPU(u16, x86_cpu_to_apicid);
DECLARE_EARLY_PER_CPU(u16, x86_bios_cpu_apicid);

------------------------------------------------------------
arch/x86/kernel/setup.c:
/* which logical CPU number maps to which CPU (physical APIC ID) */
DEFINE_EARLY_PER_CPU(u16, x86_cpu_to_apicid, BAD_APICID);
DEFINE_EARLY_PER_CPU(u16, x86_bios_cpu_apicid, BAD_APICID);
EXPORT_EARLY_PER_CPU(x86_cpu_to_apicid);
EXPORT_EARLY_PER_CPU(x86_bios_cpu_apicid);
#ifdef CONFIG_NUMA
DEFINE_EARLY_PER_CPU(int, x86_cpu_to_node, NUMA_NO_NODE);
EXPORT_EARLY_PER_CPU(x86_cpu_to_node);
#endif

...

#if defined(CONFIG_HAVE_SETUP_PER_CPU_AREA) && defined(CONFIG_SMP)
/*
* Copy data used in early init routines from the initial arrays to the
* per cpu data areas. These arrays then become expendable and the
* *_early_ptr's are zeroed indicating that the static arrays are gone.
*/
static void __init setup_per_cpu_maps(void)
{
int cpu;
for_each_possible_cpu(cpu) {
per_cpu(x86_cpu_to_apicid, cpu) =
early_per_cpu_map(x86_cpu_to_apicid, cpu);
per_cpu(x86_bios_cpu_apicid, cpu) =
early_per_cpu_map(x86_bios_cpu_apicid, cpu);
#ifdef CONFIG_NUMA
per_cpu(x86_cpu_to_node_map, cpu) =
early_per_cpu_map(x86_cpu_to_node_map, cpu);
#endif
}
/* indicate the early static arrays will soon be gone */
early_per_cpu_ptr(x86_cpu_to_apicid) = NULL;
early_per_cpu_ptr(x86_bios_cpu_apicid) = NULL;
#ifdef CONFIG_NUMA
early_per_cpu_ptr(x86_cpu_to_node_map) = NULL;
#endif
...
------------------------------------------------------------
arch/x86/mm/numa_64.c:
void __cpuinit numa_set_node(int cpu, int node)
{
int *cpu_to_node_map = early_per_cpu_ptr(x86_cpu_to_node_map);
if(cpu_to_node_map)
cpu_to_node_map[cpu] = node;
else if(per_cpu_offset(cpu))
per_cpu(x86_cpu_to_node_map, cpu) = node;
...
void __init init_cpu_to_node(void)
{
int i;
for (i = 0; i < NR_CPUS; i++) {
int node;
u16 apicid = early_per_cpu(x86_cpu_to_apicid, i);
if (apicid == BAD_APICID)
continue;
...
------------------------------------------------------------

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