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linux-next/include/linux/getcpu.h
Vojtech Pavlik c08c820508 [PATCH] Add the vgetcpu vsyscall
This patch adds a vgetcpu vsyscall, which depending on the CPU RDTSCP
capability uses either the RDTSCP or CPUID to obtain a CPU and node
numbers and pass them to the program.

AK: Lots of changes over Vojtech's original code:
Better prototype for vgetcpu()
It's better to pass the cpu / node numbers as separate arguments
to avoid mistakes when going from SMP to NUMA.
Also add a fast time stamp based cache using a user supplied
argument to speed things more up.
Use fast method from Chuck Ebbert to retrieve node/cpu from
GDT limit instead of CPUID
Made sure RDTSCP init is always executed after node is known.
Drop printk

Signed-off-by: Vojtech Pavlik <vojtech@suse.cz>
Signed-off-by: Andi Kleen <ak@suse.de>
2006-09-26 10:52:28 +02:00

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524 B
C

#ifndef _LINUX_GETCPU_H
#define _LINUX_GETCPU_H 1
/* Cache for getcpu() to speed it up. Results might be upto a jiffie
out of date, but will be faster.
User programs should not refer to the contents of this structure.
It is only a cache for vgetcpu(). It might change in future kernels.
The user program must store this information per thread (__thread)
If you want 100% accurate information pass NULL instead. */
struct getcpu_cache {
unsigned long t0;
unsigned long t1;
unsigned long res[4];
};
#endif