Support for high-precision timers on Alpha.

2024-11-23 13:30:06 +00:00 · 2001-09-01 06:08:44 +00:00 · 2001-09-01 06:08:44 +00:00 · 9f888890de
commit 9f888890de
parent 6222fd02e7
1 changed files with 118 additions and 0 deletions
--- a/sysdeps/alpha/hp-timing.h
+++ b/sysdeps/alpha/hp-timing.h
@ -0,0 +1,118 @@
+/* High precision, low overhead timing functions.  Alpha version.
+   Copyright (C) 2001 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Richard Henderson <rth@redhat.com>, 2001.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#ifndef _HP_TIMING_H
+#define _HP_TIMING_H	1
+
+#include <string.h>
+#include <sys/param.h>
+#include <stdio-common/_itoa.h>
+
+/* The macros defined here use the timestamp counter in IA-64.  They
+   provide a very accurate way to measure the time with very little
+   overhead.  The time values themself have no real meaning, only
+   differences are interesting.
+
+   The list of macros we need includes the following:
+
+   - HP_TIMING_AVAIL: test for availability.
+
+   - HP_TIMING_INLINE: this macro is non-zero if the functionality is not
+     implemented using function calls but instead uses some inlined code
+     which might simply consist of a few assembler instructions.  We have to
+     know this since we might want to use the macros here in places where we
+     cannot make function calls.
+
+   - hp_timing_t: This is the type for variables used to store the time
+     values.
+
+   - HP_TIMING_ZERO: clear `hp_timing_t' object.
+
+   - HP_TIMING_NOW: place timestamp for current time in variable given as
+     parameter.
+
+   - HP_TIMING_DIFF_INIT: do whatever is necessary to be able to use the
+     HP_TIMING_DIFF macro.
+
+   - HP_TIMING_DIFF: compute difference between two times and store it
+     in a third.  Source and destination might overlap.
+
+   - HP_TIMING_ACCUM: add time difference to another variable.  This might
+     be a bit more complicated to implement for some platforms as the
+     operation should be thread-safe and 64bit arithmetic on 32bit platforms
+     is not.
+
+   - HP_TIMING_ACCUM_NT: this is the variant for situations where we know
+     there are no threads involved.
+
+   - HP_TIMING_PRINT: write decimal representation of the timing value into
+     the given string.  This operation need not be inline even though
+     HP_TIMING_INLINE is specified.
+*/
+
+/* We always have the timestamp register, but it's got only a 4 second
+   range.  Use it for ld.so profiling only.  */
+#define HP_TIMING_AVAIL		(0)
+#define HP_SMALL_TIMING_AVAIL	(1)
+
+/* We indeed have inlined functions.  */
+#define HP_TIMING_INLINE	(1)
+
+/* We use 32 bit values for the times.  */
+typedef unsigned int hp_timing_t;
+
+/* Set timestamp value to zero.  */
+#define HP_TIMING_ZERO(VAR)	(VAR) = (0)
+
+/* The "rpcc" instruction returns a 32-bit counting half and a 32-bit
+   "virtual cycle counter displacement".  Subtracting the two gives us
+   a virtual cycle count.  */
+#define HP_TIMING_NOW(VAR) \
+  do {									      \
+    unsigned long int x_;						      \
+    asm volatile ("rpcc %0" : "=r"(x_));				      \
+    (VAR) = (int) (x_) - (int) (x_ >> 32);				      \
+  } while (0)
+
+/* ??? Two rpcc instructions can be scheduled simultaneously.  */
+#define HP_TIMING_DIFF_INIT() do { } while (0)
+
+/* It's simple arithmetic for us.  */
+#define HP_TIMING_DIFF(Diff, Start, End)	(Diff) = ((End) - (Start))
+
+/* ??? Don't bother, since we're only used for ld.so.  */
+#define HP_TIMING_ACCUM(Sum, Diff)  not implemented
+
+/* No threads, no extra work.  */
+#define HP_TIMING_ACCUM_NT(Sum, Diff)	(Sum) += (Diff)
+
+/* Print the time value.  */
+#define HP_TIMING_PRINT(Buf, Len, Val) \
+  do {									      \
+    char __buf[20];							      \
+    char *__cp = _itoa_word (Val, __buf + sizeof (__buf), 10, 0);	      \
+    int __len = (Len);							      \
+    char *__dest = (Buf);						      \
+    while (__len-- > 0 && __cp < __buf + sizeof (__buf))		      \
+      *__dest++ = *__cp++;						      \
+    memcpy (__dest, " clock cycles", MIN (__len, sizeof (" clock cycles")));  \
+  } while (0)
+
+#endif	/* hp-timing.h */