I want to do a profiling in my software using TSC, running under Linux x86_64. I tried to search on my local disk for a example and found out in SQLite3:
#elif (defined(__GNUC__) && defined(__x86_64__)) __inline__ sqlite_uint64 sqlite3Hwtime(void){ unsigned long val; __asm__ __volatile__ ("rdtsc" : "=A" (val)); return val; } I ported it into my software, but the result val is 32-bit. I've download the newest version of sqlite3, but it's the same. Then I tried to figure out using of TSC in Linux kernel: /* * both i386 and x86_64 returns 64-bit value in edx:eax, but gcc's "A" * constraint has different meanings. For i386, "A" means exactly * edx:eax, while for x86_64 it doesn't mean rdx:rax or edx:eax. Instead, * it means rax *or* rdx. */ #ifdef CONFIG_X86_64 #define DECLARE_ARGS(val, low, high) unsigned low, high #define EAX_EDX_VAL(val, low, high) ((low) | ((u64)(high) << 32)) #define EAX_EDX_ARGS(val, low, high) "a" (low), "d" (high) #define EAX_EDX_RET(val, low, high) "=a" (low), "=d" (high) #else #define DECLARE_ARGS(val, low, high) unsigned long long val #define EAX_EDX_VAL(val, low, high) (val) #define EAX_EDX_ARGS(val, low, high) "A" (val) #define EAX_EDX_RET(val, low, high) "=A" (val) #endif .............................................. static __always_inline unsigned long long __native_read_tsc(void) { DECLARE_ARGS(val, low, high); asm volatile("rdtsc" : EAX_EDX_RET(val, low, high)); return EAX_EDX_VAL(val, low, high); } Does sqlite3 intend to use 32-bit time stamp on x86_64, or this is a bug? -- Cyberman Wu _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users