[PATCH] PPC64 enable hp-timing 4th try

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

This version uses a small 1024 byte buffer on the stack. 1K is the sweet
spot and will handle up to 8 processors in the 1st read. For larger
systems (/proc/cpuinfo larger than 1023 bytes) we will read 512 bytes at
a time until we find EOF, keeping the last two 512 buffers. The last
512-1023 bytes of the file will contain the timebase value.

This will handle any number of CPUs in /proc/cpuinfo as long as timebase
value follows the CPUs.



2005-10-31  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-20051031/sysdeps/powerpc/powerpc64/Makefile libc24/sysdeps/powerpc/powerpc64/Makefile
--- libc24-cvstip-20051031/sysdeps/powerpc/powerpc64/Makefile	2005-08-04 16:35:44.000000000 -0500
+++ libc24/sysdeps/powerpc/powerpc64/Makefile	2005-10-31 15:23:55.839280856 -0600
@@ -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-20051031/sysdeps/powerpc/powerpc64/hp-timing.c libc24/sysdeps/powerpc/powerpc64/hp-timing.c
--- libc24-cvstip-20051031/sysdeps/powerpc/powerpc64/hp-timing.c	Wed Dec 31 18:00:00 1969
+++ libc24/sysdeps/powerpc/powerpc64/hp-timing.c	Mon Oct 31 15:23:55 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-20051031/sysdeps/powerpc/powerpc64/hp-timing.h libc24/sysdeps/powerpc/powerpc64/hp-timing.h
--- libc24-cvstip-20051031/sysdeps/powerpc/powerpc64/hp-timing.h	Wed Dec 31 18:00:00 1969
+++ libc24/sysdeps/powerpc/powerpc64/hp-timing.h	Mon Oct 31 15:23:55 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-20051031/sysdeps/unix/sysv/linux/powerpc/get_clockfreq.c libc24/sysdeps/unix/sysv/linux/powerpc/get_clockfreq.c
--- libc24-cvstip-20051031/sysdeps/unix/sysv/linux/powerpc/get_clockfreq.c	Wed Dec 31 18:00:00 1969
+++ libc24/sysdeps/unix/sysv/linux/powerpc/get_clockfreq.c	Mon Oct 31 17:00:47 2005
@@ -0,0 +1,106 @@
+/* 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 <libc-internal.h>
+
+
+hp_timing_t
+__get_clockfreq (void)
+{
+  /* We read the information from the /proc filesystem.  /proc/cpuinfo contains at
+     least one line like:
+        timebase        : 33333333
+     We search for this line and convert the number in 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))
+    {
+      /* The timebase will be in the 1st 1024 bytes for systems with up
+         to 8 processors.  If the first read returns less then 1024
+	 bytes read,  we have the whole cpuinfo and can start the scan.
+	 Otherwise we will have to read more to insure we have the 
+	 timebase value in the scan.  */
+      char buf[1024];
+      ssize_t n;
+
+      n = read (fd, buf, sizeof buf);
+      if (n == (sizeof buf))
+      {
+        /* We are here because the 1st read returned exactly (sizeof buf)
+	   bytes.  This implies that we are not at EOF and may not have
+	   read the timebase value yet.  So we need to read more bytes 
+	   until we know we have EOF.  We copy the lower half of buf
+	   to the upper half and read (sizeof buf)/2 bytes into the lower
+	   half of buf and repeat until we reach EOF.  We can assume 
+	   that the timebase will be in the last 512 bytes of cpuinfo,  
+	   so two 512 byte half_bufs will be sufficient to contain the 
+	   timebase and will handle the case where the timebase spans
+	   the half_buf boundry.  */
+        ssize_t half_buf = (sizeof buf)/2;
+      	while (n >= half_buf)
+	{
+	   memcpy (buf, buf+half_buf, half_buf);
+	   n = read (fd, buf+half_buf, half_buf);
+	}
+	if (n >= 0)
+	   n+= half_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;
+	}
+      close (fd);
+    }
+
+  return timebase_freq;
+}