linux/cycles.h

   1 /*
   2   Copyright (C) 2001 Paul Davis
   3   Code derived from various headers from the Linux kernel
   4
   5   This program is free software; you can redistribute it and/or modify
   6   it under the terms of the GNU General Public License as published by
   7   the Free Software Foundation; either version 2 of the License, or
   8   (at your option) any later version.
   9
  10   This program is distributed in the hope that it will be useful,
  11   but WITHOUT ANY WARRANTY; without even the implied warranty of
  12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13   GNU General Public License for more details.
  14
  15   You should have received a copy of the GNU General Public License
  16   along with this program; if not, write to the Free Software
  17   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18
  19   $Id: cycles.h,v 1.4.2.1 2006/06/20 14:44:00 letz Exp $
  20 */
  21
  22 #ifndef __jack_cycles_h__
  23 #define __jack_cycles_h__
  24
  25 /*
  26  * Standard way to access the cycle counter on i586+ CPUs.
  27  * Currently only used on SMP.
  28  *
  29  * If you really have a SMP machine with i486 chips or older,
  30  * compile for that, and this will just always return zero.
  31  * That's ok, it just means that the nicer scheduling heuristics
  32  * won't work for you.
  33  *
  34  * We only use the low 32 bits, and we'd simply better make sure
  35  * that we reschedule before that wraps. Scheduling at least every
  36  * four billion cycles just basically sounds like a good idea,
  37  * regardless of how fast the machine is.
  38  */
  39
  40 #ifdef __linux__
  41
  42 #ifdef __x86_64__
  43
  44 typedef unsigned long cycles_t;
  45 extern cycles_t cacheflush_time;
  46
  47 static inline unsigned long get_cycles(void)
  48 {
  49     unsigned int hi, lo;
  50     __asm__ __volatile__ ("rdtsc" : "=a"(lo), "=d"(hi));
  51     return (((unsigned long)hi)<<32) | ((unsigned long)lo);
  52 }
  53
  54 #endif
  55
  56 #ifdef __PPC__
  57
  58 /* PowerPC */
  59
  60 #define CPU_FTR_601                     0x00000100
  61
  62 typedef unsigned long cycles_t;
  63
  64 /* For the "cycle" counter we use the timebase lower half. */
  65
  66 extern cycles_t cacheflush_time;
  67
  68 static inline cycles_t get_cycles(void)
  69 {
  70     cycles_t ret = 0;
  71
  72     __asm__ __volatile__(
  73         "98:    mftb %0\n"
  74         "99:\n"
  75         ".section __ftr_fixup,\"a\"\n"
  76         "       .long %1\n"
  77         "       .long 0\n"
  78         "       .long 98b\n"
  79         "       .long 99b\n"
  80         ".previous"
  81     : "=r" (ret) : "i" (CPU_FTR_601));
  82     return ret;
  83 }
  84
  85 #endif
  86
  87 #ifdef __i386__
  88
  89 typedef unsigned long long cycles_t;
  90
  91 extern cycles_t cacheflush_time;
  92
  93 #define rdtscll(val) \
  94      __asm__ __volatile__("rdtsc" : "=A" (val))
  95
  96 static inline cycles_t get_cycles (void)
  97 {
  98     unsigned long long ret;
  99
 100     rdtscll(ret);
 101     return ret;
 102 }
 103
 104 #endif
 105
 106 #endif
 107
 108 #endif /* __jack_cycles_h__ */