[PATCH] PPC64 enable hp-timing 3rd try

[Steven Munroe <munroesj at us dot ibm dot com>]

This version uses malloc to allocate a 16k buffer in __get_clockfreq.

Looks like the current 64 cpu systems with SMT can generate a 
/proc/cpuinfo of around 9K.  As timebase is near the end of the file we
need at least that much to guarentee we will find the timebase value. We
can expect to see bigger systems in the future so we will allocate a 16K
buffer to be sure.  Because we are pushing PTHREAD_STACK_MIN, we use
malloc for the buffer instead of using stack space.


2005-10-25  Steven Munroe  <sjmunroe@us.ibm.com>

	* sysdeps/powerpc/powerpc64/Makefile
	(sysdep_routines, elide-routines.os): Add hp-timing.
	* sysdeps/powerpc/powerpc64/hp-timing.c: New file.
	* sysdeps/powerpc/powerpc64/hp-timing.h: New file.
	* sysdeps/unix/sysv/linux/powerpc/get_clockfreq.c: New file.

diff -urN libc24-cvstip-20051025/sysdeps/powerpc/powerpc64/Makefile libc24/sysdeps/powerpc/powerpc64/Makefile
--- libc24-cvstip-20051025/sysdeps/powerpc/powerpc64/Makefile	2005-08-04 16:35:44.000000000 -0500
+++ libc24/sysdeps/powerpc/powerpc64/Makefile	2005-10-25 15:17:00.161168888 -0500
@@ -11,6 +11,8 @@
 endif
 
 ifeq ($(subdir),csu)
+sysdep_routines += hp-timing
+elide-routines.os += hp-timing
 ifneq ($(elf),no)
 # The initfini generation code doesn't work in the presence of -fPIC, so
 # we use -fpic instead which is much better.
diff -urN libc24-cvstip-20051025/sysdeps/powerpc/powerpc64/hp-timing.c libc24/sysdeps/powerpc/powerpc64/hp-timing.c
--- libc24-cvstip-20051025/sysdeps/powerpc/powerpc64/hp-timing.c	Wed Dec 31 18:00:00 1969
+++ libc24/sysdeps/powerpc/powerpc64/hp-timing.c	Tue Oct 25 15:17:00 2005
@@ -0,0 +1,25 @@
+/* Support for high precision, low overhead timing functions. 
+   powerpc64 version.
+   Copyright (C) 2005 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
+
+   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.  */
+
+#include <hp-timing.h>
+
+/* We have to define the variable for the overhead.  */
+hp_timing_t _dl_hp_timing_overhead;
diff -urN libc24-cvstip-20051025/sysdeps/powerpc/powerpc64/hp-timing.h libc24/sysdeps/powerpc/powerpc64/hp-timing.h
--- libc24-cvstip-20051025/sysdeps/powerpc/powerpc64/hp-timing.h	Wed Dec 31 18:00:00 1969
+++ libc24/sysdeps/powerpc/powerpc64/hp-timing.h	Tue Oct 25 15:17:00 2005
@@ -0,0 +1,136 @@
+/* High precision, low overhead timing functions.  powerpc64 version.
+   Copyright (C) 2005 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
+
+   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>
+#include <atomic.h>
+
+/* The macros defined here use the powerpc 64-bit time base register.
+   The time base is nominally clocked at 1/8th the CPU clock, but this
+   can vary.
+
+   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 assume having the timestamp register.  */
+#define HP_TIMING_AVAIL		(1)
+
+/* We indeed have inlined functions.  */
+#define HP_TIMING_INLINE	(1)
+
+/* We use 64bit values for the times.  */
+typedef unsigned long long int hp_timing_t;
+
+/* Set timestamp value to zero.  */
+#define HP_TIMING_ZERO(Var)	(Var) = (0)
+
+/* That's quite simple.  Use the `mftb' instruction.  Note that the value
+   might not be 100% accurate since there might be some more instructions
+   running in this moment.  This could be changed by using a barrier like
+   'lwsync' right before the `mftb' instruciton.  But we are not interested
+   in accurate clock cycles here so we don't do this.  */
+#define HP_TIMING_NOW(Var)	__asm__ __volatile__ ("mftb %0" : "=r" (Var))
+
+/* Use two 'mftb' instructions in a row to find out how long it takes.
+   On current POWER4, POWER5, and 970 processors mftb take ~10 cycles.  */
+#define HP_TIMING_DIFF_INIT() \
+  do {									      \
+    if (GLRO(dl_hp_timing_overhead) == 0)				      \
+      {									      \
+	int __cnt = 5;							      \
+	GLRO(dl_hp_timing_overhead) = ~0ull;				      \
+	do								      \
+	  {								      \
+	    hp_timing_t __t1, __t2;					      \
+	    HP_TIMING_NOW (__t1);					      \
+	    HP_TIMING_NOW (__t2);					      \
+	    if (__t2 - __t1 < GLRO(dl_hp_timing_overhead))		      \
+	      GLRO(dl_hp_timing_overhead) = __t2 - __t1;		      \
+	  }								      \
+	while (--__cnt > 0);						      \
+      }									      \
+  } while (0)
+
+/* It's simple arithmetic in 64-bit.  */
+#define HP_TIMING_DIFF(Diff, Start, End)	(Diff) = ((End) - (Start))
+
+/* We need to insure that this add is atomic in threaded environments.  We use
+   __arch_atomic_exchange_and_add_64 from atomic.h to get thread safety.  */
+#define HP_TIMING_ACCUM(Sum, Diff) \
+  do {									      \
+    hp_timing_t __diff = (Diff) - GLRO(dl_hp_timing_overhead);		      \
+    __arch_atomic_exchange_and_add_64 (&(Sum), __diff);	                      \
+  } while (0)
+
+/* 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 (Val, __buf + sizeof (__buf), 10, 0);		      \
+    size_t __len = (Len);						      \
+    char *__dest = (Buf);						      \
+    while (__len-- > 0 && __cp < __buf + sizeof (__buf))		      \
+      *__dest++ = *__cp++;						      \
+    memcpy (__dest, " ticks", MIN (__len, sizeof (" ticks")));  \
+  } while (0)
+
+#endif	/* hp-timing.h */
diff -urN libc24-cvstip-20051025/sysdeps/unix/sysv/linux/powerpc/get_clockfreq.c libc24/sysdeps/unix/sysv/linux/powerpc/get_clockfreq.c
--- libc24-cvstip-20051025/sysdeps/unix/sysv/linux/powerpc/get_clockfreq.c	Wed Dec 31 18:00:00 1969
+++ libc24/sysdeps/unix/sysv/linux/powerpc/get_clockfreq.c	Wed Oct 26 16:36:14 2005
@@ -0,0 +1,90 @@
+/* Get frequency of the system processor.  powerpc/Linux version.
+   Copyright (C) 2000, 2001, 2005 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   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.  */
+
+#include <ctype.h>
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <libc-internal.h>
+
+#define CPUINFO_BUF 16384
+
+hp_timing_t
+__get_clockfreq (void)
+{
+  /* We read the cpuinfo from the /proc filesystem.  It contains at
+     least one line like:
+     timebase        : 33333333
+     We search for this line and convert the number into an integer.  */
+  static hp_timing_t timebase_freq;
+  hp_timing_t result = 0L;
+  int fd;
+
+  /* If this function was called before, we know the result.  */
+  if (timebase_freq != 0)
+    return timebase_freq;
+
+  fd = open ("/proc/cpuinfo", O_RDONLY);
+  if (__builtin_expect (fd != -1, 1))
+    {
+      /* Looks like the current 64 cpu systems with SMT can generate a 
+         /proc/cpuinfo of around 9K.  So we allocate a 16K buffer to be
+         sure we capture the timebase value.  Because we are pushing
+         PTHREAD_STACK_MIN, we use malloc for the buffer.  */
+      char *buf;
+      ssize_t n;
+      buf = malloc (CPUINFO_BUF);
+
+      if (__builtin_expect (buf != NULL, 1))
+	{
+	  n = read (fd, buf, CPUINFO_BUF);
+	  if (__builtin_expect (n, 1) > 0)
+	    {
+	      char *mhz = memmem (buf, n, "timebase", 7);
+
+	      if (__builtin_expect (mhz != NULL, 1))
+		{
+		  char *endp = buf + n;
+
+		  /* Search for the beginning of the string.  */
+		  while (mhz < endp && (*mhz < '0' || *mhz > '9')
+			 && *mhz != '\n')
+		    ++mhz;
+
+		  while (mhz < endp && *mhz != '\n')
+		    {
+		      if (*mhz >= '0' && *mhz <= '9')
+			{
+			  result *= 10;
+			  result += *mhz - '0';
+			}
+
+		      ++mhz;
+		    }
+		}
+	      timebase_freq = result;
+	    }
+	  free (buf);
+	}
+      close (fd);
+    }
+
+  return timebase_freq;
+}