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Tune cpuset macros to optimize cases when CPU_SETSIZE fits into single

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machine word. For example, it turns CPU_SET() into expected shift and OR,
removing two extra shifts and additional index on memory access.

Generated code checked for kernel (optimized) and user-level (unoptimized)
cases with GCC and CLANG.

Reviewed by:	attilio
MFC after:	2 weeks
This commit is contained in:
Alexander Motin 2012-03-12 07:02:16 +00:00
parent 9437b8d495
commit 3907c073e5
1 changed files with 14 additions and 7 deletions
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21
sys/sys/cpuset.h
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@ -36,11 +36,18 @@
#define CPUSETBUFSIZ ((2 + sizeof(long) * 2) * _NCPUWORDS)
#define __cpuset_mask(n) ((long)1 << ((n) % _NCPUBITS))
#define CPU_CLR(n, p) ((p)->__bits[(n)/_NCPUBITS] &= ~__cpuset_mask(n))
/*
* Macros addressing word and bit within it, tuned to make compiler
* optimize cases when CPU_SETSIZE fits into single machine word.
*/
#define __cpuset_mask(n) \
((long)1 << ((_NCPUWORDS == 1) ? (__size_t)(n) : ((n) % _NCPUBITS)))
#define __cpuset_word(n) ((_NCPUWORDS == 1) ? 0 : ((n) / _NCPUBITS))
#define CPU_CLR(n, p) ((p)->__bits[__cpuset_word(n)] &= ~__cpuset_mask(n))
#define CPU_COPY(f, t) (void)(*(t) = *(f))
#define CPU_ISSET(n, p) (((p)->__bits[(n)/_NCPUBITS] & __cpuset_mask(n)) != 0)
#define CPU_SET(n, p) ((p)->__bits[(n)/_NCPUBITS] |= __cpuset_mask(n))
#define CPU_ISSET(n, p) (((p)->__bits[__cpuset_word(n)] & __cpuset_mask(n)) != 0)
#define CPU_SET(n, p) ((p)->__bits[__cpuset_word(n)] |= __cpuset_mask(n))
#define CPU_ZERO(p) do { \
__size_t __i; \
for (__i = 0; __i < _NCPUWORDS; __i++) \
@ -55,7 +62,7 @@
#define CPU_SETOF(n, p) do { \
CPU_ZERO(p); \
((p)->__bits[(n)/_NCPUBITS] = __cpuset_mask(n)); \
((p)->__bits[__cpuset_word(n)] = __cpuset_mask(n)); \
} while (0)
/* Is p empty. */
@ -126,10 +133,10 @@
} while (0)
#define CPU_CLR_ATOMIC(n, p) \
atomic_clear_long(&(p)->__bits[(n)/_NCPUBITS], __cpuset_mask(n))
atomic_clear_long(&(p)->__bits[__cpuset_word(n)], __cpuset_mask(n))
#define CPU_SET_ATOMIC(n, p) \
atomic_set_long(&(p)->__bits[(n)/_NCPUBITS], __cpuset_mask(n))
atomic_set_long(&(p)->__bits[__cpuset_word(n)], __cpuset_mask(n))
/* Convenience functions catering special cases. */
#define CPU_OR_ATOMIC(d, s) do { \