sysdeps/mach/hurd/profil.c

   1 /* Low-level statistical profiling support function.  Mach/Hurd version.
   2    Copyright (C) 1995, 1996, 1997 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library 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 GNU
  13    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <sys/types.h>
  21 #include <unistd.h>
  22 #include <errno.h>
  23 #include <hurd.h>
  24 #include <mach/mach4.h>
  25 #include <mach/pc_sample.h>
  26 #include <cthreads.h>
  27 #include <assert.h>
  28
  29 #define MAX_PC_SAMPLES  512     /* XXX ought to be exported in kernel hdr */
  30
  31 static thread_t profile_thread = MACH_PORT_NULL;
  32 static u_short *samples;
  33 static size_t maxsamples;
  34 static size_t pc_offset;
  35 static size_t sample_scale;
  36 static sampled_pc_seqno_t seqno;
  37 static struct mutex lock = MUTEX_INITIALIZER;
  38 static mach_msg_timeout_t collector_timeout; /* ms between collections.  */
  39 static int profile_tick;
  40
  41 /* Enable statistical profiling, writing samples of the PC into at most
  42    SIZE bytes of SAMPLE_BUFFER; every processor clock tick while profiling
  43    is enabled, the system examines the user PC and increments
  44    SAMPLE_BUFFER[((PC - OFFSET) / 2) * SCALE / 65536].  If SCALE is zero,
  45    disable profiling.  Returns zero on success, -1 on error.  */
  46
  47 static error_t
  48 update_waiter (u_short *sample_buffer, size_t size, size_t offset, u_int scale)
  49 {
  50   error_t err;
  51
  52   if (profile_thread == MACH_PORT_NULL)
  53     {
  54       /* Set up the profiling collector thread.  */
  55       static void profile_waiter (void);
  56       err = __thread_create (__mach_task_self (), &profile_thread);
  57       if (! err)
  58         err = __mach_setup_thread (__mach_task_self (), profile_thread,
  59                                    &profile_waiter, NULL, NULL);
  60     }
  61   else
  62     err = 0;
  63
  64   if (! err)
  65     {
  66       err = __task_enable_pc_sampling (__mach_task_self (), &profile_tick,
  67                                        SAMPLED_PC_PERIODIC);
  68       if (!err && sample_scale == 0)
  69         /* Profiling was not turned on, so the collector thread was
  70            suspended.  Resume it.  */
  71         err = __thread_resume (profile_thread);
  72       if (! err)
  73         {
  74           samples = sample_buffer;
  75           maxsamples = size / sizeof *sample_buffer;
  76           pc_offset = offset;
  77           sample_scale = scale;
  78           /* Calculate a good period for the collector thread.  From TICK
  79              and the kernel buffer size we get the length of time it takes
  80              to fill the buffer; translate that to milliseconds for
  81              mach_msg, and chop it in half for general lag factor.  */
  82           collector_timeout = MAX_PC_SAMPLES * profile_tick / 1000 / 2;
  83         }
  84     }
  85
  86   return err;
  87 }
  88
  89 int
  90 __profile_frequency ()
  91 {
  92   return profile_tick;
  93 }
  94
  95 int
  96 profil (u_short *sample_buffer, size_t size, size_t offset, u_int scale)
  97 {
  98   error_t err;
  99
 100   __mutex_lock (&lock);
 101
 102   if (scale == 0)
 103     {
 104       /* Disable profiling.  */
 105       int count;
 106       __thread_suspend (profile_thread);
 107       err = __task_disable_pc_sampling (__mach_task_self (), &count);
 108       sample_scale = 0;
 109       seqno = 0;
 110     }
 111   else
 112     err = update_waiter (sample_buffer, size, offset, scale);
 113
 114   __mutex_unlock (&lock);
 115
 116   return err ? __hurd_fail (err) : 0;
 117 }
 118
 119 static void
 120 profile_waiter (void)
 121 {
 122   sampled_pc_t pc_samples[MAX_PC_SAMPLES];
 123   mach_msg_type_number_t nsamples, i;
 124   mach_port_t rcv = __mach_reply_port ();
 125   mach_msg_header_t msg;
 126   error_t err;
 127
 128   while (1)
 129     {
 130       __mutex_lock (&lock);
 131
 132       nsamples = sizeof pc_samples / sizeof pc_samples[0];
 133       err = __task_get_sampled_pcs (__mach_task_self (), &seqno,
 134                                     pc_samples, &nsamples);
 135       assert_perror (err);
 136
 137       for (i = 0; i < nsamples; ++i)
 138         {
 139           size_t idx = (((pc_samples[i].pc - pc_offset) / 2) *
 140                         sample_scale / 65536);
 141           if (idx < maxsamples)
 142             ++samples[idx];
 143         }
 144
 145       __vm_deallocate (__mach_task_self (),
 146                        (vm_address_t) pc_samples,
 147                        nsamples * sizeof *pc_samples);
 148
 149       __mutex_unlock (&lock);
 150
 151       __mach_msg (&msg, MACH_RCV_MSG|MACH_RCV_TIMEOUT, 0, sizeof msg,
 152                   rcv, collector_timeout, MACH_PORT_NULL);
 153     }
 154 }
 155 \f
 156 data_set_element (_hurd_fork_locks, lock);
 157
 158 static void
 159 fork_profil (void)
 160 {
 161   u_short *sb;
 162   size_t n, o, ss;
 163   error_t err;
 164
 165   if (profile_thread != MACH_PORT_NULL)
 166     {
 167       __mach_port_deallocate (__mach_task_self (), profile_thread);
 168       profile_thread = MACH_PORT_NULL;
 169     }
 170
 171   sb = samples;
 172   samples = NULL;
 173   n = maxsamples;
 174   maxsamples = 0;
 175   o = pc_offset;
 176   pc_offset = 0;
 177   ss = sample_scale;
 178   sample_scale = 0;
 179
 180   if (ss != 0)
 181     {
 182       err = update_waiter (sb, n * sizeof *sb, o, ss);
 183       assert_perror (err);
 184     }
 185 }
 186 text_set_element (_hurd_fork_child_hook, fork_profil);