cycles.h

00001 /*
00002   Copyright (C) 2001 Paul Davis
00003   Code derived from various headers from the Linux kernel
00004   
00005   This program is free software; you can redistribute it and/or modify
00006   it under the terms of the GNU General Public License as published by
00007   the Free Software Foundation; either version 2 of the License, or
00008   (at your option) any later version.
00009 
00010   This program is distributed in the hope that it will be useful,
00011   but WITHOUT ANY WARRANTY; without even the implied warranty of
00012   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00013   GNU General Public License for more details.
00014 
00015   You should have received a copy of the GNU General Public License
00016   along with this program; if not, write to the Free Software
00017   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
00018 
00019   $Id: cycles.h,v 1.4.2.1 2006/06/20 14:44:00 letz Exp $
00020 */
00021 
00022 #ifndef __jack_cycles_h__
00023 #define __jack_cycles_h__
00024 
00025 /*
00026  * Standard way to access the cycle counter on i586+ CPUs.
00027  * Currently only used on SMP.
00028  *
00029  * If you really have a SMP machine with i486 chips or older,
00030  * compile for that, and this will just always return zero.
00031  * That's ok, it just means that the nicer scheduling heuristics
00032  * won't work for you.
00033  *
00034  * We only use the low 32 bits, and we'd simply better make sure
00035  * that we reschedule before that wraps. Scheduling at least every
00036  * four billion cycles just basically sounds like a good idea,
00037  * regardless of how fast the machine is. 
00038  */
00039 
00040 #ifdef __linux__
00041 
00042 #ifdef __PPC__
00043 
00044 /* PowerPC */
00045 
00046 #define CPU_FTR_601                     0x00000100
00047 
00048 typedef unsigned long cycles_t;
00049 
00050 /* For the "cycle" counter we use the timebase lower half. */
00051 
00052 extern cycles_t cacheflush_time;
00053 
00054 static inline cycles_t get_cycles(void)
00055 {
00056     cycles_t ret = 0;
00057 
00058     __asm__ __volatile__(
00059         "98:    mftb %0\n"
00060         "99:\n"
00061         ".section __ftr_fixup,\"a\"\n"
00062         "       .long %1\n"
00063         "       .long 0\n"
00064         "       .long 98b\n"
00065         "       .long 99b\n"
00066         ".previous"
00067     : "=r" (ret) : "i" (CPU_FTR_601));
00068     return ret;
00069 }
00070 
00071 #endif
00072 
00073 #ifdef __i386__
00074 
00075 typedef unsigned long long cycles_t;
00076 
00077 extern cycles_t cacheflush_time;
00078 
00079 #define rdtscll(val) \
00080      __asm__ __volatile__("rdtsc" : "=A" (val))
00081 
00082 static inline cycles_t get_cycles (void)
00083 {
00084     unsigned long long ret;
00085 
00086     rdtscll(ret);
00087     return ret;
00088 }
00089 
00090 #endif
00091 
00092 #endif
00093 
00094 #endif /* __jack_cycles_h__ */

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