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*
144 #+gencgc (* 4 (expt 10 6))
145 ;; Stop-and-copy GC is really really slow when used too often. CSR
146 ;; reported that even on his old 64 Mb SPARC, 20 Mb is much faster
147 ;; than 4 Mb when rebuilding SBCL ca. 0.7.1. For modern machines
148 ;; with >> 128 Mb memory, the optimum could be significantly more
149 ;; than this, but at least 20 Mb should be better than 4 Mb.
150 #-gencgc (* 20 (expt 10 6)))
151 (declaim (type index *bytes-consed-between-gcs*))
155 (defvar *before-gc-hooks* nil ; actually initialized in cold init
157 "A list of functions that are called before garbage collection occurs.
158 The functions should take no arguments.")
160 (defvar *after-gc-hooks* nil ; actually initialized in cold init
162 "A list of functions that are called after garbage collection occurs.
163 The functions should take no arguments.")
165 (defvar *gc-notify-stream* nil ; (actually initialized in cold init)
167 "When non-NIL, this must be a STREAM; and the functions bound to
168 *GC-NOTIFY-BEFORE* and *GC-NOTIFY-AFTER* are called with the
169 STREAM value before and after a garbage collection occurs
172 (defvar *gc-run-time* 0
174 "the total CPU time spent doing garbage collection (as reported by
175 GET-INTERNAL-RUN-TIME)")
176 (declaim (type index *gc-run-time*))
178 ;;; a limit to help catch programs which allocate too much memory,
179 ;;; since a hard heap overflow is so hard to recover from
180 (declaim (type (or unsigned-byte null) *soft-heap-limit*))
181 (defvar *soft-heap-limit* nil)
183 ;;; When the dynamic usage increases beyond this amount, the system
184 ;;; notes that a garbage collection needs to occur by setting
185 ;;; *NEED-TO-COLLECT-GARBAGE* to T. It starts out as NIL meaning
186 ;;; nobody has figured out what it should be yet.
187 (defvar *gc-trigger* nil)
189 (declaim (type (or index null) *gc-trigger*))
191 ;;; On the X86, we store the GC trigger in a ``static'' symbol instead
192 ;;; of letting magic C code handle it. It gets initialized by the
195 (defvar sb!vm::*internal-gc-trigger*)
197 ;;;; The following specials are used to control when garbage collection
200 ;;; When non-NIL, inhibits garbage collection.
201 (defvar *gc-inhibit*) ; initialized in cold init
203 ;;; This flag is used to prevent recursive entry into the garbage
205 (defvar *already-maybe-gcing*) ; initialized in cold init
207 ;;; When T, indicates that the dynamic usage has exceeded the value
209 (defvar *need-to-collect-garbage* nil) ; initialized in cold init
211 (defun default-gc-notify-before (notify-stream bytes-in-use)
212 (declare (type stream notify-stream))
215 "~&; GC is beginning with ~:D bytes in use at internal runtime ~:D.~%"
217 (get-internal-run-time))
218 (finish-output notify-stream))
219 (defparameter *gc-notify-before* #'default-gc-notify-before
221 "This function bound to this variable is invoked before GC'ing (unless
222 *GC-NOTIFY-STREAM* is NIL) with the value of *GC-NOTIFY-STREAM* and
223 current amount of dynamic usage (in bytes). It should notify the
224 user that the system is going to GC.")
226 (defun default-gc-notify-after (notify-stream
230 (declare (type stream notify-stream))
231 (format notify-stream
232 "~&; GC has finished with ~:D bytes in use (~:D bytes freed)~@
233 ; at internal runtime ~:D. The new GC trigger is ~:D bytes.~%"
236 (get-internal-run-time)
238 (finish-output notify-stream))
239 (defparameter *gc-notify-after* #'default-gc-notify-after
241 "The function bound to this variable is invoked after GC'ing with the
242 value of *GC-NOTIFY-STREAM*, the amount of dynamic usage (in bytes) now
243 free, the number of bytes freed by the GC, and the new GC trigger
244 threshold; or if *GC-NOTIFY-STREAM* is NIL, it's not invoked. The
245 function should notify the user that the system has finished GC'ing.")
249 (sb!alien:define-alien-routine collect-garbage sb!alien:int
250 #!+gencgc (last-gen sb!alien:int))
252 (sb!alien:define-alien-routine set-auto-gc-trigger sb!alien:void
253 (dynamic-usage sb!alien:unsigned-long))
255 (sb!alien:define-alien-routine clear-auto-gc-trigger sb!alien:void)
257 ;;; This variable contains the function that does the real GC. This is
258 ;;; for low-level GC experimentation. Do not touch it if you do not
259 ;;; know what you are doing.
260 (defvar *internal-gc* #'collect-garbage)
264 ;;; This is used to carefully invoke hooks.
265 (eval-when (:compile-toplevel :execute)
266 (sb!xc:defmacro carefully-funcall (function &rest args)
267 `(handler-case (funcall ,function ,@args)
269 (warn "(FUNCALL ~S~{ ~S~}) lost:~%~A" ',function ',args cond)
272 ;;; SUB-GC decides when and if to do a garbage collection. The FORCE-P
273 ;;; flags controls whether a GC should occur even if the dynamic usage
274 ;;; is not greater than *GC-TRIGGER*.
276 ;;; For GENCGC all generations < GEN will be GC'ed.
277 (defun sub-gc (&key force-p (gen 0))
278 (/show0 "entering SUB-GC")
279 (unless *already-maybe-gcing*
280 (let* ((*already-maybe-gcing* t)
281 (start-time (get-internal-run-time))
282 (pre-gc-dynamic-usage (dynamic-usage))
283 ;; Currently we only check *SOFT-HEAP-LIMIT* at GC time,
284 ;; not for every allocation. That makes it cheap to do,
285 ;; even if it is a little ugly.
286 (soft-heap-limit-exceeded? (and *soft-heap-limit*
287 (> pre-gc-dynamic-usage
289 (*soft-heap-limit* (if soft-heap-limit-exceeded?
290 (+ pre-gc-dynamic-usage
291 *bytes-consed-between-gcs*)
293 (when soft-heap-limit-exceeded?
294 (cerror "Continue with GC."
295 "soft heap limit exceeded (temporary new limit=~W)"
297 (when (and *gc-trigger* (> pre-gc-dynamic-usage *gc-trigger*))
298 (setf *need-to-collect-garbage* t))
300 (and *need-to-collect-garbage* (not *gc-inhibit*)))
301 ;; KLUDGE: Wow, we really mask interrupts all the time we're
302 ;; collecting garbage? That seems like a long time.. -- WHN 19991129
304 ;; FIXME: We probably shouldn't do this evil thing to
305 ;; *STANDARD-OUTPUT* in a binding which is wrapped around
306 ;; calls to user-settable GC hook functions.
307 (let ((*standard-output* *terminal-io*))
308 (when *gc-notify-stream*
309 (if (streamp *gc-notify-stream*)
310 (carefully-funcall *gc-notify-before*
312 pre-gc-dynamic-usage)
314 "*GC-NOTIFY-STREAM* is set, but not a STREAM -- ignored.")))
315 (dolist (hook *before-gc-hooks*)
316 (carefully-funcall hook))
318 (clear-auto-gc-trigger))
319 (let* (;; We do DYNAMIC-USAGE once more here in order to
320 ;; get a more accurate measurement of the space
321 ;; actually freed, since the messing around, e.g.
322 ;; GC-notify stuff, since the DYNAMIC-USAGE which
323 ;; triggered GC could've done a fair amount of
325 (pre-internal-gc-dynamic-usage (dynamic-usage))
327 #!-gencgc (funcall *internal-gc*)
328 ;; FIXME: This EQ test is pretty gross. Among its other
329 ;; nastinesses, it looks as though it could break if we
330 ;; recompile COLLECT-GARBAGE. We should probably just
331 ;; straighten out the interface so that all *INTERNAL-GC*
332 ;; functions accept a GEN argument (and then the
333 ;; non-generational ones just ignore it).
334 #!+gencgc (if (eq *internal-gc* #'collect-garbage)
335 (funcall *internal-gc* gen)
336 (funcall *internal-gc*)))
337 (post-gc-dynamic-usage (dynamic-usage))
338 (n-bytes-freed (- pre-internal-gc-dynamic-usage
339 post-gc-dynamic-usage))
340 ;; In sbcl-0.6.12.39, the raw N-BYTES-FREED from
341 ;; GENCGC could sometimes be substantially negative
342 ;; (e.g. -5872). I haven't looked into what causes
343 ;; that, but I suspect it has to do with
344 ;; fluctuating inefficiency in the way that the
345 ;; GENCGC packs things into page boundaries.
346 ;; Bumping the raw result up to 0 is a little ugly,
347 ;; but shouldn't be a problem, and it's even
348 ;; possible to sort of justify it: the packing
349 ;; inefficiency which has caused (DYNAMIC-USAGE) to
350 ;; grow is effectively consing, or at least
351 ;; overhead of consing, so it's sort of correct to
352 ;; add it to the running total of consing. ("Man
353 ;; isn't a rational animal, he's a rationalizing
354 ;; animal.":-) -- WHN 2001-06-23
355 (eff-n-bytes-freed (max 0 n-bytes-freed)))
356 (declare (ignore ignore-me))
357 (/show0 "got (DYNAMIC-USAGE) and EFF-N-BYTES-FREED")
358 (incf *n-bytes-freed-or-purified*
360 (/show0 "clearing *NEED-TO-COLLECT-GARBAGE*")
361 (setf *need-to-collect-garbage* nil)
362 (/show0 "calculating NEW-GC-TRIGGER")
363 (let ((new-gc-trigger (+ post-gc-dynamic-usage
364 *bytes-consed-between-gcs*)))
365 (/show0 "setting *GC-TRIGGER*")
366 (setf *gc-trigger* new-gc-trigger))
367 (/show0 "calling SET-AUTO-GC-TRIGGER")
368 (set-auto-gc-trigger *gc-trigger*)
369 (dolist (hook *after-gc-hooks*)
370 (/show0 "doing a hook from *AFTER-GC--HOOKS*")
371 ;; FIXME: This hook should be called with the same
372 ;; kind of information as *GC-NOTIFY-AFTER*. In
373 ;; particular, it would be nice for the hook function
374 ;; to be able to adjust *GC-TRIGGER* intelligently to
375 ;; e.g. 108% of total memory usage.
376 (carefully-funcall hook))
377 (when *gc-notify-stream*
378 (if (streamp *gc-notify-stream*)
379 (carefully-funcall *gc-notify-after*
381 post-gc-dynamic-usage
385 "*GC-NOTIFY-STREAM* is set, but not a stream -- ignored.")))))
386 (scrub-control-stack))) ;XXX again? we did this from C ...
387 (incf *gc-run-time* (- (get-internal-run-time)
389 ;; FIXME: should probably return (VALUES), here and in RETURN-FROM
392 ;;; This routine is called by the allocation miscops to decide whether
393 ;;; a GC should occur. The argument, OBJECT, is the newly allocated
394 ;;; object which must be returned to the caller.
395 (defun maybe-gc (&optional object)
399 ;;; This is the user-advertised garbage collection function.
400 (defun gc (&key (gen 0) (full nil) &allow-other-keys)
401 #!+(and sb-doc gencgc)
402 "Initiate a garbage collection. GEN controls the number of generations
404 #!+(and sb-doc (not gencgc))
405 "Initiate a garbage collection. GEN may be provided for compatibility with
406 generational garbage collectors, but is ignored in this implementation."
407 (sub-gc :force-p t :gen (if full 6 gen)))
410 ;;;; auxiliary functions
412 (defun bytes-consed-between-gcs ()
414 "Return the amount of memory that will be allocated before the next garbage
415 collection is initiated. This can be set with SETF."
416 *bytes-consed-between-gcs*)
417 (defun (setf bytes-consed-between-gcs) (val)
418 ;; FIXME: Shouldn't this (and the DECLAIM for the underlying variable)
419 ;; be for a strictly positive number type, e.g.
420 ;; (AND (INTEGER 1) FIXNUM)?
421 (declare (type index val))
422 (let ((old *bytes-consed-between-gcs*))
423 (setf *bytes-consed-between-gcs* val)
425 (setf *gc-trigger* (+ *gc-trigger* (- val old)))
426 (cond ((<= (dynamic-usage) *gc-trigger*)
427 (clear-auto-gc-trigger)
428 (set-auto-gc-trigger *gc-trigger*))
430 ;; FIXME: If SCRUB-CONTROL-STACK is required here, why
431 ;; isn't it built into SUB-GC? And *is* it required here?
432 (sb!sys:scrub-control-stack)
438 "Enable the garbage collector."
439 (setq *gc-inhibit* nil)
440 (when *need-to-collect-garbage*
446 "Disable the garbage collector."
447 (setq *gc-inhibit* t)
450 ;;;; initialization stuff
454 (if (< *gc-trigger* (dynamic-usage))
456 (set-auto-gc-trigger *gc-trigger*))))