diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/my_cpu.h | 54 |
1 files changed, 41 insertions, 13 deletions
diff --git a/include/my_cpu.h b/include/my_cpu.h index b5665fc108c..0e37eafe60e 100644 --- a/include/my_cpu.h +++ b/include/my_cpu.h @@ -46,10 +46,20 @@ #define HMT_high() #endif +#if defined __i386__ || defined __x86_64__ || defined _WIN32 +# define HAVE_PAUSE_INSTRUCTION /* added in Intel Pentium 4 */ +#endif static inline void MY_RELAX_CPU(void) { -#ifdef HAVE_PAUSE_INSTRUCTION +#ifdef _WIN32 + /* + In the Win32 API, the x86 PAUSE instruction is executed by calling + the YieldProcessor macro defined in WinNT.h. It is a CPU architecture- + independent way by using YieldProcessor. + */ + YieldProcessor(); +#elif defined HAVE_PAUSE_INSTRUCTION /* According to the gcc info page, asm volatile means that the instruction has important side-effects and must not be removed. @@ -61,16 +71,6 @@ static inline void MY_RELAX_CPU(void) #else __asm__ __volatile__ ("pause"); #endif - -#elif defined(HAVE_FAKE_PAUSE_INSTRUCTION) - __asm__ __volatile__ ("rep; nop"); -#elif defined _WIN32 - /* - In the Win32 API, the x86 PAUSE instruction is executed by calling - the YieldProcessor macro defined in WinNT.h. It is a CPU architecture- - independent way by using YieldProcessor. - */ - YieldProcessor(); #elif defined(_ARCH_PWR8) __ppc_get_timebase(); #else @@ -81,6 +81,20 @@ static inline void MY_RELAX_CPU(void) } +#ifdef HAVE_PAUSE_INSTRUCTION +# ifdef __cplusplus +extern "C" { +# endif +extern unsigned my_cpu_relax_multiplier; +void my_cpu_init(void); +# ifdef __cplusplus +} +# endif +#else +# define my_cpu_relax_multiplier 200 +# define my_cpu_init() /* nothing */ +#endif + /* LF_BACKOFF should be used to improve performance on hyperthreaded CPUs. Intel recommends to use it in spin loops also on non-HT machines to reduce power @@ -94,9 +108,23 @@ static inline void MY_RELAX_CPU(void) static inline int LF_BACKOFF(void) { - int i; - for (i= 0; i < 200; i++) + unsigned i= my_cpu_relax_multiplier; + while (i--) MY_RELAX_CPU(); return 1; } + +/** + Run a delay loop while waiting for a shared resource to be released. + @param delay originally, roughly microseconds on 100 MHz Intel Pentium +*/ +static inline void ut_delay(unsigned delay) +{ + unsigned i= my_cpu_relax_multiplier / 4 * delay; + HMT_low(); + while (i--) + MY_RELAX_CPU(); + HMT_medium(); +} + #endif |