diff options
author | markm <markm@FreeBSD.org> | 2000-11-21 19:55:21 +0000 |
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committer | markm <markm@FreeBSD.org> | 2000-11-21 19:55:21 +0000 |
commit | 92be31d0b583b42dee21f006ea62f231ad132326 (patch) | |
tree | d6b561d8a67702e3c67ef7b6a1873d03c8cc57cc /sys/alpha/include/cpu.h | |
parent | dfa19cb0cec51bbb1fba802ceae5f4b58cad3892 (diff) | |
download | FreeBSD-src-92be31d0b583b42dee21f006ea62f231ad132326.zip FreeBSD-src-92be31d0b583b42dee21f006ea62f231ad132326.tar.gz |
Add a consistent API to a feature that most modern CPUs have; a fast
counter register in-CPU.
This is to be used as a fast "timer", where linearity is more important
than time, and multiple lines in the linearity caused by multiple CPUs
in an SMP machine is not a problem.
This adds no code whatsoever to the FreeBSD kernel until it is actually
used, and then as a single-instruction inline routine (except for the
80386 and 80486 where it is some more inline code around nanotime(9).
Reviewed by: bde, kris, jhb
Diffstat (limited to 'sys/alpha/include/cpu.h')
-rw-r--r-- | sys/alpha/include/cpu.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/sys/alpha/include/cpu.h b/sys/alpha/include/cpu.h index a45b4d1..a0be38f 100644 --- a/sys/alpha/include/cpu.h +++ b/sys/alpha/include/cpu.h @@ -173,6 +173,16 @@ void syscall __P((u_int64_t, struct trapframe *)); void trap __P((unsigned long, unsigned long, unsigned long, unsigned long, struct trapframe *)); +/* + * Return contents of in-cpu fast counter as a sort of "bogo-time" + * for non-critical timing. + */ +static __inline u_int64_t +get_cyclecount(void) +{ + return (alpha_rpcc()); +} + #endif /* _KERNEL */ #endif /* _ALPHA_CPU_H_ */ |