src/include/gpxe/profile.h

   1 #ifndef _GPXE_PROFILE_H
   2 #define _GPXE_PROFILE_H
   3
   4 /** @file
   5  *
   6  * Profiling
   7  *
   8  */
   9
  10 FILE_LICENCE ( GPL2_OR_LATER );
  11
  12 #include <stdint.h>
  13
  14 /**
  15  * A data structure for storing profiling information
  16  */
  17 union profiler {
  18         /** Timestamp (in CPU-specific "ticks") */
  19         uint64_t timestamp;
  20         /** Registers returned by rdtsc.
  21          *
  22          * This part should really be architecture-specific code.
  23          */
  24         struct {
  25                 uint32_t eax;
  26                 uint32_t edx;
  27         } rdtsc;
  28 };
  29
  30 /**
  31  * Static per-object profiler, for use with simple_profile()
  32  */
  33 static union profiler simple_profiler;
  34
  35 /**
  36  * Perform profiling
  37  *
  38  * @v profiler          Profiler data structure
  39  * @ret delta           Elapsed ticks since last call to profile().
  40  *
  41  * Call profile() both before and after the code you wish to measure.
  42  * The "after" call will return the measurement.  For example:
  43  *
  44  * @code
  45  *
  46  *     profile ( &profiler );
  47  *     ... do something here ...
  48  *     printf ( "It took %ld ticks to execute\n", profile ( &profiler ) );
  49  *
  50  * @endcode
  51  */
  52 static inline __attribute__ (( always_inline )) unsigned long
  53 profile ( union profiler *profiler ) {
  54         uint64_t last_timestamp = profiler->timestamp;
  55
  56         __asm__ __volatile__ ( "rdtsc" :
  57                                "=a" ( profiler->rdtsc.eax ),
  58                                "=d" ( profiler->rdtsc.edx ) );
  59         return ( profiler->timestamp - last_timestamp );
  60 }
  61
  62 /**
  63  * Perform profiling
  64  *
  65  * @ret delta           Elapsed ticks since last call to profile().
  66  *
  67  * When you only need one profiler, you can avoid the hassle of
  68  * creating your own @c profiler data structure by using
  69  * simple_profile() instead.
  70  *
  71  * simple_profile() is equivalent to profile(&simple_profiler), where
  72  * @c simple_profiler is a @c profiler data structure that is static
  73  * to each object which includes @c profile.h.
  74  */
  75 static inline __attribute__ (( always_inline )) unsigned long
  76 simple_profile ( void ) {
  77         return profile ( &simple_profiler );
  78 }
  79
  80 #endif /* _GPXE_PROFILE_H */