1 /* Low-level statistical profiling support function. Mach/Hurd version.
2 Copyright (C) 1995, 1996, 1997, 2000, 2002, 2005 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
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 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
20 #include <sys/types.h>
24 #include <mach/mach4.h>
25 #include <mach/pc_sample.h>
28 #include <libc-internal.h>
31 #define MAX_PC_SAMPLES 512 /* XXX ought to be exported in kernel hdr */
33 static thread_t profile_thread
= MACH_PORT_NULL
;
34 static u_short
*samples
;
35 static size_t maxsamples
;
36 static size_t pc_offset
;
37 static size_t sample_scale
;
38 static sampled_pc_seqno_t seqno
;
39 static spin_lock_t lock
= SPIN_LOCK_INITIALIZER
;
40 static mach_msg_timeout_t collector_timeout
; /* ms between collections. */
41 static int profile_tick
;
43 /* Reply port used by profiler thread */
44 static mach_port_t profil_reply_port
;
47 static kern_return_t
profil_task_get_sampled_pcs (mach_port_t
,
50 mach_msg_type_number_t
*);
51 static void fetch_samples (void);
52 static void profile_waiter (void);
54 /* Enable statistical profiling, writing samples of the PC into at most
55 SIZE bytes of SAMPLE_BUFFER; every processor clock tick while profiling
56 is enabled, the system examines the user PC and increments
57 SAMPLE_BUFFER[((PC - OFFSET) / 2) * SCALE / 65536]. If SCALE is zero,
58 disable profiling. Returns zero on success, -1 on error. */
61 update_waiter (u_short
*sample_buffer
, size_t size
, size_t offset
, u_int scale
)
65 if (profile_thread
== MACH_PORT_NULL
)
67 /* Set up the profiling collector thread. */
68 err
= __thread_create (__mach_task_self (), &profile_thread
);
70 err
= __mach_setup_thread (__mach_task_self (), profile_thread
,
71 &profile_waiter
, NULL
, NULL
);
78 err
= __task_enable_pc_sampling (__mach_task_self (), &profile_tick
,
80 if (!err
&& sample_scale
== 0)
81 /* Profiling was not turned on, so the collector thread was
82 suspended. Resume it. */
83 err
= __thread_resume (profile_thread
);
86 samples
= sample_buffer
;
87 maxsamples
= size
/ sizeof *sample_buffer
;
90 /* Calculate a good period for the collector thread. From TICK
91 and the kernel buffer size we get the length of time it takes
92 to fill the buffer; translate that to milliseconds for
93 mach_msg, and chop it in half for general lag factor. */
94 collector_timeout
= MAX_PC_SAMPLES
* profile_tick
/ 1000 / 2;
102 __profile_frequency (void)
106 libc_hidden_def (__profile_frequency
)
109 __profil (u_short
*sample_buffer
, size_t size
, size_t offset
, u_int scale
)
117 /* Disable profiling. */
120 if (profile_thread
!= MACH_PORT_NULL
)
121 __thread_suspend (profile_thread
);
123 /* Fetch the last set of samples */
127 err
= __task_disable_pc_sampling (__mach_task_self (), &count
);
132 err
= update_waiter (sample_buffer
, size
, offset
, scale
);
134 __spin_unlock (&lock
);
136 return err
? __hurd_fail (err
) : 0;
138 weak_alias (__profil
, profil
)
140 /* Fetch PC samples. This function must be very careful not to depend
141 on Hurd threadvar variables. We arrange that by using a special
142 stub arranged for at the end of this file. */
146 sampled_pc_t pc_samples
[MAX_PC_SAMPLES
];
147 mach_msg_type_number_t nsamples
, i
;
150 nsamples
= MAX_PC_SAMPLES
;
152 err
= profil_task_get_sampled_pcs (__mach_task_self (), &seqno
,
153 pc_samples
, &nsamples
);
156 static error_t special_profil_failure
;
157 static volatile int a
, b
, c
;
159 special_profil_failure
= err
;
166 for (i
= 0; i
< nsamples
; ++i
)
168 /* Do arithmetic in long long to avoid overflow problems. */
169 long long pc_difference
= pc_samples
[i
].pc
- pc_offset
;
170 size_t idx
= ((pc_difference
/ 2) * sample_scale
) / 65536;
171 if (idx
< maxsamples
)
177 /* This function must be very careful not to depend on Hurd threadvar
178 variables. We arrange that by using special stubs arranged for at the
181 profile_waiter (void)
183 mach_msg_header_t msg
;
184 mach_port_t timeout_reply_port
;
186 profil_reply_port
= __mach_reply_port ();
187 timeout_reply_port
= __mach_reply_port ();
195 __spin_unlock (&lock
);
197 __mach_msg (&msg
, MACH_RCV_MSG
|MACH_RCV_TIMEOUT
, 0, sizeof msg
,
198 timeout_reply_port
, collector_timeout
, MACH_PORT_NULL
);
202 /* Fork interaction */
204 /* Before fork, lock the interlock so that we are in a clean state. */
206 fork_profil_prepare (void)
210 text_set_element (_hurd_fork_prepare_hook
, fork_profil_prepare
);
212 /* In the parent, unlock the interlock once fork is complete. */
214 fork_profil_parent (void)
216 __spin_unlock (&lock
);
218 text_set_element (_hurd_fork_parent_hook
, fork_profil_parent
);
220 /* In the childs, unlock the interlock, and start a profiling thread up
223 fork_profil_child (void)
229 __spin_unlock (&lock
);
231 if (profile_thread
!= MACH_PORT_NULL
)
233 __mach_port_deallocate (__mach_task_self (), profile_thread
);
234 profile_thread
= MACH_PORT_NULL
;
248 err
= update_waiter (sb
, n
* sizeof *sb
, o
, ss
);
252 text_set_element (_hurd_fork_child_hook
, fork_profil_child
);
257 /* Special RPC stubs for profile_waiter are made by including the normal
258 source code, with special CPP state to prevent it from doing the
261 /* Include these first; then our #define's will take full effect, not
263 #include <mach/mig_support.h>
265 /* This need not do anything; it is always associated with errors, which
266 are fatal in profile_waiter anyhow. */
267 #define __mig_put_reply_port(foo)
269 /* Use our static variable instead of the usual threadvar mechanism for
271 #define __mig_get_reply_port() profil_reply_port
273 /* Make the functions show up as static */
274 #define mig_external static
276 /* Turn off the attempt to generate ld aliasing records. */
278 #define weak_alias(a,b)
280 /* And change their names to avoid confusing disasters. */
281 #define __vm_deallocate_rpc profil_vm_deallocate
282 #define __task_get_sampled_pcs profil_task_get_sampled_pcs
284 /* And include the source code */
285 #include <../mach/RPC_task_get_sampled_pcs.c>