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1 /* Why the hell is XEmacs so fucking slow?
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2 Copyright (C) 1996 Ben Wing.
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3
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4 This file is part of XEmacs.
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5
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6 XEmacs is free software; you can redistribute it and/or modify it
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7 under the terms of the GNU General Public License as published by the
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8 Free Software Foundation; either version 2, or (at your option) any
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9 later version.
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10
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11 XEmacs is distributed in the hope that it will be useful, but WITHOUT
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12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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14 for more details.
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15
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16 You should have received a copy of the GNU General Public License
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17 along with XEmacs; see the file COPYING. If not, write to
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18 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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19 Boston, MA 02111-1307, USA. */
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20
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21 #include <config.h>
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22 #include "lisp.h"
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23
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24 #include "backtrace.h"
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25 #include "bytecode.h"
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26 #include "hash.h"
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27
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28 #include "syssignal.h"
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29 #include "systime.h"
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30
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31 /*
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32
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33 We implement our own profiling scheme so that we can determine things
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34 like which Lisp functions are occupying the most time. Any standard
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35 OS-provided profiling works on C functions, which is somewhat useless.
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36
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37 The basic idea is simple. We set a profiling timer using
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38 setitimer (ITIMER_PROF), which generates a SIGPROF every so often.
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39 \(This runs not in real time but rather when the process is executing
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40 or the system is running on behalf of the process.) When the signal
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41 goes off, we see what we're in, and add by 1 the count associated with
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42 that function.
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43
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44 It would be nice to use the Lisp allocation mechanism etc. to keep
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45 track of the profiling information, but we can't because that's not
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46 safe, and trying to make it safe would be much more work than is
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47 worth.
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48
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49 */
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50
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51 c_hashtable big_profile_table;
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52
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53 int default_profiling_interval;
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54
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55 int profiling_active;
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56
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57 /* The normal flag in_display is used as a critical-section flag
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58 and is not set the whole time we're in redisplay. */
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59 int profiling_redisplay_flag;
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60
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61 Lisp_Object QSin_redisplay;
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62 Lisp_Object QSin_garbage_collection;
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63 Lisp_Object QSprocessing_events_at_top_level;
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64 Lisp_Object QSunknown;
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65
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116
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66 /* We use inside_profiling to prevent the handler from writing to
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67 the table while another routine is operating on it. We also set
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68 inside_profiling in case the timeout between signal calls is short
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69 enough to catch us while we're already in there. */
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149
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70 static volatile int inside_profiling;
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116
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71
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0
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72 static SIGTYPE
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73 sigprof_handler (int signo)
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74 {
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116
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75 /* Don't do anything if we are shutting down, or are doing a maphash
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76 or clrhash on the table. */
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77 if (!inside_profiling && !preparing_for_armageddon)
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78 {
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79 Lisp_Object fun;
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80
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81 /* If something below causes an error to be signaled, we'll
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82 not correctly reset this flag. But we'll be in worse shape
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83 than that anyways, since we'll longjmp back to the last
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84 condition case. */
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85 inside_profiling = 1;
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86
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87 if (profiling_redisplay_flag)
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88 fun = QSin_redisplay;
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89 else if (gc_in_progress)
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90 fun = QSin_garbage_collection;
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91 else if (backtrace_list)
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92 {
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93 fun = *backtrace_list->function;
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44
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94
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116
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95 if (!GC_SYMBOLP (fun) && !GC_COMPILED_FUNCTIONP (fun))
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96 fun = QSunknown;
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97 }
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98 else
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99 fun = QSprocessing_events_at_top_level;
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0
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100
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116
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101 {
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102 /* #### see comment about memory allocation in start-profiling.
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103 Allocating memory in a signal handler is BAD BAD BAD.
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104 If you are using the non-mmap rel-alloc code, you might
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185
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105 lose because of this. Even worse, if the memory allocation
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106 fails, the `error' generated whacks everything hard. */
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107 long count;
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108 CONST void *vval;
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185
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109
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110 if (gethash (LISP_TO_VOID (fun), big_profile_table, &vval))
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111 count = (long) vval;
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112 else
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113 count = 0;
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114 count++;
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115 vval = (CONST void *) count;
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116 puthash (LISP_TO_VOID (fun), (void *) vval, big_profile_table);
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117 }
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185
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118
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116
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119 inside_profiling = 0;
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70
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120 }
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121 }
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122
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123 DEFUN ("start-profiling", Fstart_profiling, 0, 1, 0, /*
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124 Start profiling, with profile queries every MICROSECS.
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125 If MICROSECS is nil or omitted, the value of `default-profiling-interval'
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126 is used.
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127
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128 You can retrieve the recorded profiling info using `get-profiling-info'.
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129
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130 Starting and stopping profiling does not clear the currently recorded
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131 info. Thus you can start and stop as many times as you want and everything
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20
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132 will be properly accumulated.
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133 */
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134 (microsecs))
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135 {
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116
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136 /* This function can GC */
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137 int msecs;
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138 struct itimerval foo;
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139
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140 /* #### The hash code can safely be called from a signal handler
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141 except when it has to grow the hashtable. In this case, it calls
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142 realloc(), which is not (in general) re-entrant. We just be
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143 sleazy and make the table large enough that it (hopefully) won't
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144 need to be realloc()ed. */
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145 if (!big_profile_table)
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146 big_profile_table = make_hashtable (10000);
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147 if (NILP (microsecs))
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148 msecs = default_profiling_interval;
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149 else
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150 {
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151 CHECK_NATNUM (microsecs);
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152 msecs = XINT (microsecs);
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153 }
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154 if (msecs <= 0)
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155 msecs = 1000;
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156
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157 signal (SIGPROF, sigprof_handler);
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158 foo.it_value.tv_sec = 0;
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159 foo.it_value.tv_usec = msecs;
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160 EMACS_NORMALIZE_TIME (foo.it_value);
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161 foo.it_interval = foo.it_value;
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162 profiling_active = 1;
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163 inside_profiling = 0;
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164 setitimer (ITIMER_PROF, &foo, 0);
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165 return Qnil;
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166 }
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167
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168 DEFUN ("stop-profiling", Fstop_profiling, 0, 0, 0, /*
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169 Stop profiling.
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170 */
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171 ())
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172 {
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173 /* This function does not GC */
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174 struct itimerval foo;
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175
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176 foo.it_value.tv_sec = 0;
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177 foo.it_value.tv_usec = 0;
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178 foo.it_interval = foo.it_value;
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179 setitimer (ITIMER_PROF, &foo, 0);
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180 profiling_active = 0;
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181 signal (SIGPROF, fatal_error_signal);
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182 return Qnil;
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183 }
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184
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185 static Lisp_Object
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186 profile_lock_unwind (Lisp_Object ignore)
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187 {
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185
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188 inside_profiling = 0;
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189 return Qnil;
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190 }
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191
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192 struct get_profiling_info_closure
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193 {
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194 Lisp_Object accum;
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195 };
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196
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197 static void
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198 get_profiling_info_maphash (CONST void *void_key,
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199 void *void_val,
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200 void *void_closure)
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201 {
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202 /* This function does not GC */
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203 Lisp_Object key;
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204 struct get_profiling_info_closure *closure
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205 = (struct get_profiling_info_closure *) void_closure;
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206 EMACS_INT val;
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207
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208 CVOID_TO_LISP (key, void_key);
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209 val = (EMACS_INT) void_val;
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210
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211 closure->accum = Fcons (Fcons (key, make_int (val)), closure->accum);
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212 }
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213
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214 DEFUN ("get-profiling-info", Fget_profiling_info, 0, 0, 0, /*
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215 Return the profiling info as an alist.
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216 */
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217 ())
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218 {
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219 /* This function does not GC */
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220 struct get_profiling_info_closure closure;
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221
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222 closure.accum = Qnil;
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223 if (big_profile_table)
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116
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224 {
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225 int count = specpdl_depth ();
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226 record_unwind_protect (profile_lock_unwind, Qnil);
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227 inside_profiling = 1;
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228 maphash (get_profiling_info_maphash, big_profile_table, &closure);
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229 unbind_to (count, Qnil);
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230 }
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231 return closure.accum;
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232 }
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233
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234 struct mark_profiling_info_closure
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235 {
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236 void (*markfun) (Lisp_Object);
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237 };
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238
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239 static void
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240 mark_profiling_info_maphash (CONST void *void_key,
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241 void *void_val,
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242 void *void_closure)
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243 {
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244 Lisp_Object key;
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245
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246 CVOID_TO_LISP (key, void_key);
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247 (((struct mark_profiling_info_closure *) void_closure)->markfun) (key);
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0
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248 }
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249
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250 void
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251 mark_profiling_info (void (*markfun) (Lisp_Object))
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252 {
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253 /* This function does not GC (if markfun doesn't) */
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254 struct mark_profiling_info_closure closure;
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255
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256 closure.markfun = markfun;
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257 if (big_profile_table)
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258 {
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259 inside_profiling = 1;
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260 maphash (mark_profiling_info_maphash, big_profile_table, &closure);
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261 inside_profiling = 0;
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262 }
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263 }
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264
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199
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265 DEFUN ("clear-profiling-info", Fclear_profiling_info, 0, 0, "", /*
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266 Clear out the recorded profiling info.
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267 */
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268 ())
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269 {
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270 /* This function does not GC */
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271 if (big_profile_table)
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272 {
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273 inside_profiling = 1;
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274 clrhash (big_profile_table);
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275 inside_profiling = 0;
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276 }
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277 return Qnil;
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278 }
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279
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280 DEFUN ("profiling-active-p", Fprofiling_active_p, 0, 0, 0, /*
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281 Return non-nil if profiling information is currently being recorded.
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282 */
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283 ())
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284 {
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285 return profiling_active ? Qt : Qnil;
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286 }
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287
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288 void
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289 syms_of_profile (void)
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290 {
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291 DEFSUBR (Fstart_profiling);
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292 DEFSUBR (Fstop_profiling);
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293 DEFSUBR (Fget_profiling_info);
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294 DEFSUBR (Fclear_profiling_info);
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295 DEFSUBR (Fprofiling_active_p);
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0
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296 }
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297
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298 void
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299 vars_of_profile (void)
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300 {
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301 DEFVAR_INT ("default-profiling-interval", &default_profiling_interval /*
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302 Default time in microseconds between profiling queries.
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303 Used when the argument to `start-profiling' is nil or omitted.
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304 Note that the time in question is CPU time (when the program is executing
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305 or the kernel is executing on behalf of the program) and not real time.
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306 */ );
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307 default_profiling_interval = 1000;
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308
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309 inside_profiling = 0;
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310
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311 QSin_redisplay = build_string ("(in redisplay)");
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312 staticpro (&QSin_redisplay);
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313 QSin_garbage_collection = build_string ("(in garbage collection)");
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314 staticpro (&QSin_garbage_collection);
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315 QSunknown = build_string ("(unknown)");
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316 staticpro (&QSunknown);
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317 QSprocessing_events_at_top_level =
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318 build_string ("(processing events at top level)");
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319 staticpro (&QSprocessing_events_at_top_level);
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320 }
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