Author: mav
Date: Mon Mar 12 07:02:16 2012
New Revision: 232852
URL: http://svn.freebsd.org/changeset/base/232852
Log:
Tune cpuset macros to optimize cases when CPU_SETSIZE fits into single
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
Modified:
head/sys/sys/cpuset.h
Modified: head/sys/sys/cpuset.h
==============================================================================
--- head/sys/sys/cpuset.h Mon Mar 12 05:28:02 2012 (r232851)
+++ head/sys/sys/cpuset.h Mon Mar 12 07:02:16 2012 (r232852)
@@ -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 { \
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