1 ;;;; garbage collection and allocation-related code
3 ;;;; This software is part of the SBCL system. See the README file for
6 ;;;; This software is derived from the CMU CL system, which was
7 ;;;; written at Carnegie Mellon University and released into the
8 ;;;; public domain. The software is in the public domain and is
9 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
10 ;;;; files for more information.
12 (in-package "SB!KERNEL")
14 ;;;; DYNAMIC-USAGE and friends
16 (declaim (special sb!vm:*read-only-space-free-pointer*
17 sb!vm:*static-space-free-pointer*))
19 (eval-when (:compile-toplevel :execute)
20 (sb!xc:defmacro def-c-var-frob (lisp-fun c-var-name)
22 #!-sb-fluid (declaim (inline ,lisp-fun))
24 (sb!alien:extern-alien ,c-var-name (sb!alien:unsigned 32))))))
28 ;; This is called once per PROFILEd function call, so it's worth a
29 ;; little possible space cost to reduce its time cost.
31 (declaim (inline current-dynamic-space-start))
32 (def-c-var-frob current-dynamic-space-start "current_dynamic_space"))
35 (declaim (inline dynamic-usage)) ; to reduce PROFILEd call overhead
37 (def-c-var-frob dynamic-usage "bytes_allocated")
39 (defun dynamic-usage ()
40 (the (unsigned-byte 32)
41 (- (sb!sys:sap-int (sb!c::dynamic-space-free-pointer))
42 (current-dynamic-space-start))))
44 (defun static-space-usage ()
45 (- (* sb!vm:*static-space-free-pointer* sb!vm:n-word-bytes)
46 sb!vm:static-space-start))
48 (defun read-only-space-usage ()
49 (- (* sb!vm::*read-only-space-free-pointer* sb!vm:n-word-bytes)
50 sb!vm:read-only-space-start))
52 (defun control-stack-usage ()
53 #!-x86 (- (sb!sys:sap-int (sb!c::control-stack-pointer-sap))
54 sb!vm:control-stack-start)
55 #!+x86 (- sb!vm:control-stack-end
56 (sb!sys:sap-int (sb!c::control-stack-pointer-sap))))
58 (defun binding-stack-usage ()
59 (- (sb!sys:sap-int (sb!c::binding-stack-pointer-sap))
60 sb!vm:binding-stack-start))
64 (defun room-minimal-info ()
65 (format t "Dynamic space usage is: ~10:D bytes.~%" (dynamic-usage))
66 (format t "Read-only space usage is: ~10:D bytes.~%" (read-only-space-usage))
67 (format t "Static space usage is: ~10:D bytes.~%" (static-space-usage))
68 (format t "Control stack usage is: ~10:D bytes.~%" (control-stack-usage))
69 (format t "Binding stack usage is: ~10:D bytes.~%" (binding-stack-usage))
70 (format t "Garbage collection is currently ~:[enabled~;DISABLED~].~%"
73 (defun room-intermediate-info ()
75 (sb!vm:memory-usage :count-spaces '(:dynamic)
80 (defun room-maximal-info ()
82 (sb!vm:memory-usage :count-spaces '(:static :dynamic))
83 (sb!vm:instance-usage :dynamic :top-n 10)
84 (sb!vm:instance-usage :static :top-n 10))
86 (defun room (&optional (verbosity :default))
88 "Print to *STANDARD-OUTPUT* information about the state of internal
89 storage and its management. The optional argument controls the
90 verbosity of output. If it is T, ROOM prints out a maximal amount of
91 information. If it is NIL, ROOM prints out a minimal amount of
92 information. If it is :DEFAULT or it is not supplied, ROOM prints out
93 an intermediate amount of information."
101 (room-intermediate-info)))
104 ;;;; GET-BYTES-CONSED
106 ;;; the total number of bytes freed so far (including any freeing
107 ;;; which goes on in PURIFY)
109 ;;; (We save this so that we can calculate the total number of bytes
110 ;;; ever allocated by adding this to the number of bytes currently
111 ;;; allocated and never freed.)
112 (declaim (type unsigned-byte *n-bytes-freed-or-purified*))
113 (defvar *n-bytes-freed-or-purified* 0)
115 (setf *n-bytes-freed-or-purified* 0))
116 ;; KLUDGE: It's probably not quite safely right either to do
117 ;; this in *BEFORE-SAVE-INITIALIZATIONS* (since consing, or even
118 ;; worse, something which depended on (GET-BYTES-CONSED), might
119 ;; happen after that) or in *AFTER-SAVE-INITIALIZATIONS*. But
120 ;; it's probably not a big problem, and there seems to be no
121 ;; other obvious time to do it. -- WHN 2001-07-30
122 *after-save-initializations*)
124 (declaim (ftype (function () unsigned-byte) get-bytes-consed))
125 (defun get-bytes-consed ()
127 "Return the number of bytes consed since the program began. Typically
128 this result will be a consed bignum, so if you have an application (e.g.
129 profiling) which can't tolerate the overhead of consing bignums, you'll
130 probably want either to hack in at a lower level (as the code in the
131 SB-PROFILE package does), or to design a more microefficient interface
132 and submit it as a patch."
134 *n-bytes-freed-or-purified*))
136 ;;;; variables and constants
138 ;;; the minimum amount of dynamic space which must be consed before a
139 ;;; GC will be triggered
141 ;;; Unlike CMU CL, we don't export this variable. (There's no need to,
142 ;;; since our BYTES-CONSED-BETWEEN-GCS function is SETFable.)
143 (defvar *bytes-consed-between-gcs* (* 4 (expt 10 6)))
144 (declaim (type index *bytes-consed-between-gcs*))
148 (defvar *before-gc-hooks* nil ; actually initialized in cold init
150 "A list of functions that are called before garbage collection occurs.
151 The functions should take no arguments.")
153 (defvar *after-gc-hooks* nil ; actually initialized in cold init
155 "A list of functions that are called after garbage collection occurs.
156 The functions should take no arguments.")
158 (defvar *gc-notify-stream* nil ; (actually initialized in cold init)
160 "When non-NIL, this must be a STREAM; and the functions bound to
161 *GC-NOTIFY-BEFORE* and *GC-NOTIFY-AFTER* are called with the
162 STREAM value before and after a garbage collection occurs
165 (defvar *gc-run-time* 0
167 "the total CPU time spent doing garbage collection (as reported by
168 GET-INTERNAL-RUN-TIME)")
169 (declaim (type index *gc-run-time*))
171 ;;; a limit to help catch programs which allocate too much memory,
172 ;;; since a hard heap overflow is so hard to recover from
173 (declaim (type (or unsigned-byte null) *soft-heap-limit*))
174 (defvar *soft-heap-limit* nil)
176 ;;; When the dynamic usage increases beyond this amount, the system
177 ;;; notes that a garbage collection needs to occur by setting
178 ;;; *NEED-TO-COLLECT-GARBAGE* to T. It starts out as NIL meaning
179 ;;; nobody has figured out what it should be yet.
180 (defvar *gc-trigger* nil)
182 (declaim (type (or index null) *gc-trigger*))
184 ;;; On the X86, we store the GC trigger in a ``static'' symbol instead
185 ;;; of letting magic C code handle it. It gets initialized by the
188 (defvar sb!vm::*internal-gc-trigger*)
190 ;;;; The following specials are used to control when garbage collection
193 ;;; When non-NIL, inhibits garbage collection.
194 (defvar *gc-inhibit*) ; initialized in cold init
196 ;;; This flag is used to prevent recursive entry into the garbage
198 (defvar *already-maybe-gcing*) ; initialized in cold init
200 ;;; When T, indicates that the dynamic usage has exceeded the value
202 (defvar *need-to-collect-garbage* nil) ; initialized in cold init
204 (defun default-gc-notify-before (notify-stream bytes-in-use)
205 (declare (type stream notify-stream))
208 "~&; GC is beginning with ~:D bytes in use at internal runtime ~:D.~%"
210 (get-internal-run-time))
211 (finish-output notify-stream))
212 (defparameter *gc-notify-before* #'default-gc-notify-before
214 "This function bound to this variable is invoked before GC'ing (unless
215 *GC-NOTIFY-STREAM* is NIL) with the value of *GC-NOTIFY-STREAM* and
216 current amount of dynamic usage (in bytes). It should notify the
217 user that the system is going to GC.")
219 (defun default-gc-notify-after (notify-stream
223 (declare (type stream notify-stream))
224 (format notify-stream
225 "~&; GC has finished with ~:D bytes in use (~:D bytes freed)~@
226 ; at internal runtime ~:D. The new GC trigger is ~:D bytes.~%"
229 (get-internal-run-time)
231 (finish-output notify-stream))
232 (defparameter *gc-notify-after* #'default-gc-notify-after
234 "The function bound to this variable is invoked after GC'ing with the
235 value of *GC-NOTIFY-STREAM*, the amount of dynamic usage (in bytes) now
236 free, the number of bytes freed by the GC, and the new GC trigger
237 threshold; or if *GC-NOTIFY-STREAM* is NIL, it's not invoked. The
238 function should notify the user that the system has finished GC'ing.")
242 (sb!alien:define-alien-routine collect-garbage sb!alien:int
243 #!+gencgc (last-gen sb!alien:int))
245 (sb!alien:define-alien-routine set-auto-gc-trigger sb!alien:void
246 (dynamic-usage sb!alien:unsigned-long))
248 (sb!alien:define-alien-routine clear-auto-gc-trigger sb!alien:void)
250 ;;; This variable contains the function that does the real GC. This is
251 ;;; for low-level GC experimentation. Do not touch it if you do not
252 ;;; know what you are doing.
253 (defvar *internal-gc* #'collect-garbage)
257 ;;; This is used to carefully invoke hooks.
258 (eval-when (:compile-toplevel :execute)
259 (sb!xc:defmacro carefully-funcall (function &rest args)
260 `(handler-case (funcall ,function ,@args)
262 (warn "(FUNCALL ~S~{ ~S~}) lost:~%~A" ',function ',args cond)
265 ;;; SUB-GC decides when and if to do a garbage collection. The FORCE-P
266 ;;; flags controls whether a GC should occur even if the dynamic usage
267 ;;; is not greater than *GC-TRIGGER*.
269 ;;; For GENCGC all generations < GEN will be GC'ed.
270 (defun sub-gc (&key force-p (gen 0))
271 (/show0 "entering SUB-GC")
272 (unless *already-maybe-gcing*
273 (let* ((*already-maybe-gcing* t)
274 (start-time (get-internal-run-time))
275 (pre-gc-dynamic-usage (dynamic-usage))
276 ;; Currently we only check *SOFT-HEAP-LIMIT* at GC time,
277 ;; not for every allocation. That makes it cheap to do,
278 ;; even if it is a little ugly.
279 (soft-heap-limit-exceeded? (and *soft-heap-limit*
280 (> pre-gc-dynamic-usage
282 (*soft-heap-limit* (if soft-heap-limit-exceeded?
283 (+ pre-gc-dynamic-usage
284 *bytes-consed-between-gcs*)
286 (when soft-heap-limit-exceeded?
287 (cerror "Continue with GC."
288 "soft heap limit exceeded (temporary new limit=~W)"
290 (when (and *gc-trigger* (> pre-gc-dynamic-usage *gc-trigger*))
291 (setf *need-to-collect-garbage* t))
293 (and *need-to-collect-garbage* (not *gc-inhibit*)))
294 ;; KLUDGE: Wow, we really mask interrupts all the time we're
295 ;; collecting garbage? That seems like a long time.. -- WHN 19991129
297 ;; FIXME: We probably shouldn't do this evil thing to
298 ;; *STANDARD-OUTPUT* in a binding which is wrapped around
299 ;; calls to user-settable GC hook functions.
300 (let ((*standard-output* *terminal-io*))
301 (when *gc-notify-stream*
302 (if (streamp *gc-notify-stream*)
303 (carefully-funcall *gc-notify-before*
305 pre-gc-dynamic-usage)
307 "*GC-NOTIFY-STREAM* is set, but not a STREAM -- ignored.")))
308 (dolist (hook *before-gc-hooks*)
309 (carefully-funcall hook))
311 (clear-auto-gc-trigger))
312 (let* (;; We do DYNAMIC-USAGE once more here in order to
313 ;; get a more accurate measurement of the space
314 ;; actually freed, since the messing around, e.g.
315 ;; GC-notify stuff, since the DYNAMIC-USAGE which
316 ;; triggered GC could've done a fair amount of
318 (pre-internal-gc-dynamic-usage (dynamic-usage))
320 #!-gencgc (funcall *internal-gc*)
321 ;; FIXME: This EQ test is pretty gross. Among its other
322 ;; nastinesses, it looks as though it could break if we
323 ;; recompile COLLECT-GARBAGE. We should probably just
324 ;; straighten out the interface so that all *INTERNAL-GC*
325 ;; functions accept a GEN argument (and then the
326 ;; non-generational ones just ignore it).
327 #!+gencgc (if (eq *internal-gc* #'collect-garbage)
328 (funcall *internal-gc* gen)
329 (funcall *internal-gc*)))
330 (post-gc-dynamic-usage (dynamic-usage))
331 (n-bytes-freed (- pre-internal-gc-dynamic-usage
332 post-gc-dynamic-usage))
333 ;; In sbcl-0.6.12.39, the raw N-BYTES-FREED from
334 ;; GENCGC could sometimes be substantially negative
335 ;; (e.g. -5872). I haven't looked into what causes
336 ;; that, but I suspect it has to do with
337 ;; fluctuating inefficiency in the way that the
338 ;; GENCGC packs things into page boundaries.
339 ;; Bumping the raw result up to 0 is a little ugly,
340 ;; but shouldn't be a problem, and it's even
341 ;; possible to sort of justify it: the packing
342 ;; inefficiency which has caused (DYNAMIC-USAGE) to
343 ;; grow is effectively consing, or at least
344 ;; overhead of consing, so it's sort of correct to
345 ;; add it to the running total of consing. ("Man
346 ;; isn't a rational animal, he's a rationalizing
347 ;; animal.":-) -- WHN 2001-06-23
348 (eff-n-bytes-freed (max 0 n-bytes-freed)))
349 (declare (ignore ignore-me))
350 (/show0 "got (DYNAMIC-USAGE) and EFF-N-BYTES-FREED")
351 (incf *n-bytes-freed-or-purified*
353 (/show0 "clearing *NEED-TO-COLLECT-GARBAGE*")
354 (setf *need-to-collect-garbage* nil)
355 (/show0 "calculating NEW-GC-TRIGGER")
356 (let ((new-gc-trigger (+ post-gc-dynamic-usage
357 *bytes-consed-between-gcs*)))
358 (/show0 "setting *GC-TRIGGER*")
359 (setf *gc-trigger* new-gc-trigger))
360 (/show0 "calling SET-AUTO-GC-TRIGGER")
361 (set-auto-gc-trigger *gc-trigger*)
362 (dolist (hook *after-gc-hooks*)
363 (/show0 "doing a hook from *AFTER-GC--HOOKS*")
364 ;; FIXME: This hook should be called with the same
365 ;; kind of information as *GC-NOTIFY-AFTER*. In
366 ;; particular, it would be nice for the hook function
367 ;; to be able to adjust *GC-TRIGGER* intelligently to
368 ;; e.g. 108% of total memory usage.
369 (carefully-funcall hook))
370 (when *gc-notify-stream*
371 (if (streamp *gc-notify-stream*)
372 (carefully-funcall *gc-notify-after*
374 post-gc-dynamic-usage
378 "*GC-NOTIFY-STREAM* is set, but not a stream -- ignored.")))))
379 (scrub-control-stack))) ;XXX again? we did this from C ...
380 (incf *gc-run-time* (- (get-internal-run-time)
382 ;; FIXME: should probably return (VALUES), here and in RETURN-FROM
385 ;;; This routine is called by the allocation miscops to decide whether
386 ;;; a GC should occur. The argument, OBJECT, is the newly allocated
387 ;;; object which must be returned to the caller.
388 (defun maybe-gc (&optional object)
392 ;;; This is the user-advertised garbage collection function.
393 (defun gc (&key (gen 0) (full nil) &allow-other-keys)
394 #!+(and sb-doc gencgc)
395 "Initiate a garbage collection. GEN controls the number of generations
397 #!+(and sb-doc (not gencgc))
398 "Initiate a garbage collection. GEN may be provided for compatibility with
399 generational garbage collectors, but is ignored in this implementation."
400 (sub-gc :force-p t :gen (if full 6 gen)))
403 ;;;; auxiliary functions
405 (defun bytes-consed-between-gcs ()
407 "Return the amount of memory that will be allocated before the next garbage
408 collection is initiated. This can be set with SETF."
409 *bytes-consed-between-gcs*)
410 (defun (setf bytes-consed-between-gcs) (val)
411 ;; FIXME: Shouldn't this (and the DECLAIM for the underlying variable)
412 ;; be for a strictly positive number type, e.g.
413 ;; (AND (INTEGER 1) FIXNUM)?
414 (declare (type index val))
415 (let ((old *bytes-consed-between-gcs*))
416 (setf *bytes-consed-between-gcs* val)
418 (setf *gc-trigger* (+ *gc-trigger* (- val old)))
419 (cond ((<= (dynamic-usage) *gc-trigger*)
420 (clear-auto-gc-trigger)
421 (set-auto-gc-trigger *gc-trigger*))
423 ;; FIXME: If SCRUB-CONTROL-STACK is required here, why
424 ;; isn't it built into SUB-GC? And *is* it required here?
425 (sb!sys:scrub-control-stack)
431 "Enable the garbage collector."
432 (setq *gc-inhibit* nil)
433 (when *need-to-collect-garbage*
439 "Disable the garbage collector."
440 (setq *gc-inhibit* t)
443 ;;;; initialization stuff
447 (if (< *gc-trigger* (dynamic-usage))
449 (set-auto-gc-trigger *gc-trigger*))))