1erts_alloc(3) C Library Functions erts_alloc(3)
2
6 erts_alloc - An Erlang runtime system internal memory allocator li‐
7 brary.
8
11 erts_alloc is an Erlang runtime system internal memory allocator li‐
12 brary. erts_alloc provides the Erlang runtime system with a number of
13 memory allocators.
14
16 The following allocators are present:
17 temp_alloc:
19 Allocator used for temporary allocations.
20 eheap_alloc:
22 Allocator used for Erlang heap data, such as Erlang process heaps.
23 binary_alloc:
25 Allocator used for Erlang binary data.
26 ets_alloc:
28 Allocator used for ets data.
29 driver_alloc:
31 Allocator used for driver data.
32 literal_alloc:
34 Allocator used for constant terms in Erlang code.
35 sl_alloc:
37 Allocator used for memory blocks that are expected to be short-
38 lived.
39 ll_alloc:
41 Allocator used for memory blocks that are expected to be long-
42 lived, for example, Erlang code.
43 fix_alloc:
45 A fast allocator used for some frequently used fixed size data
46 types.
47 exec_alloc:
49 Allocator used by the HiPE application for native executable code.
50 std_alloc:
52 Allocator used for most memory blocks not allocated through any of
53 the other allocators described above.
54 sys_alloc:
56 This is normally the default malloc implementation used on the spe‐
57 cific OS.
58 mseg_alloc:
60 A memory segment allocator. It is used by other allocators for al‐
61 locating memory segments and is only available on systems that have
62 the mmap system call. Memory segments that are deallocated are kept
63 for a while in a segment cache before they are destroyed. When seg‐
64 ments are allocated, cached segments are used if possible instead
65 of creating new segments. This to reduce the number of system calls
66 made.
67 sys_alloc, literal_alloc and temp_alloc are always enabled and cannot
69 be disabled. exec_alloc is only available if it is needed and cannot be
70 disabled. mseg_alloc is always enabled if it is available and an allo‐
71 cator that uses it is enabled. All other allocators can be enabled or
72 disabled. By default all allocators are enabled. When an allocator is
73 disabled, sys_alloc is used instead of the disabled allocator.
74 The main idea with the erts_alloc library is to separate memory blocks
76 that are used differently into different memory areas, to achieve less
77 memory fragmentation. By putting less effort in finding a good fit for
78 memory blocks that are frequently allocated than for those less fre‐
79 quently allocated, a performance gain can be achieved.
80
82 Internally a framework called alloc_util is used for implementing allo‐
83 cators. sys_alloc and mseg_alloc do not use this framework, so the fol‐
84 lowing does not apply to them.
85 An allocator manages multiple areas, called carriers, in which memory
87 blocks are placed. A carrier is either placed in a separate memory seg‐
88 ment (allocated through mseg_alloc), or in the heap segment (allocated
89 through sys_alloc).
90 * Multiblock carriers are used for storage of several blocks.
92 * Singleblock carriers are used for storage of one block.
94 * Blocks that are larger than the value of the singleblock carrier
96 threshold (sbct) parameter are placed in singleblock carriers.
97 * Blocks that are smaller than the value of parameter sbct are placed
99 in multiblock carriers.
100 Normally an allocator creates a "main multiblock carrier". Main multi‐
102 block carriers are never deallocated. The size of the main multiblock
103 carrier is determined by the value of parameter mmbcs.
104 Sizes of multiblock carriers allocated through mseg_alloc are decided
106 based on the following parameters:
107 * The values of the largest multiblock carrier size (lmbcs)
109 * The smallest multiblock carrier size (smbcs)
111 * The multiblock carrier growth stages (mbcgs)
113 If nc is the current number of multiblock carriers (the main multiblock
115 carrier excluded) managed by an allocator, the size of the next
116 mseg_alloc multiblock carrier allocated by this allocator is roughly
117 smbcs+nc*(lmbcs-smbcs)/mbcgs when nc <= mbcgs, and lmbcs when nc >
118 mbcgs. If the value of parameter sbct is larger than the value of pa‐
119 rameter lmbcs, the allocator may have to create multiblock carriers
120 that are larger than the value of parameter lmbcs, though. Singleblock
121 carriers allocated through mseg_alloc are sized to whole pages.
122 Sizes of carriers allocated through sys_alloc are decided based on the
124 value of the sys_alloc carrier size (ycs) parameter. The size of a car‐
125 rier is the least number of multiples of the value of parameter ycs
126 satisfying the request.
127 Coalescing of free blocks are always performed immediately. Boundary
129 tags (headers and footers) in free blocks are used, which makes the
130 time complexity for coalescing constant.
131 The memory allocation strategy used for multiblock carriers by an allo‐
133 cator can be configured using parameter as. The following strategies
134 are available:
135 Best fit:
137 Strategy: Find the smallest block satisfying the requested block
138 size.
139 Implementation: A balanced binary search tree is used. The time
141 complexity is proportional to log N, where N is the number of sizes
142 of free blocks.
143 Address order best fit:
145 Strategy: Find the smallest block satisfying the requested block
146 size. If multiple blocks are found, choose the one with the lowest
147 address.
148 Implementation: A balanced binary search tree is used. The time
150 complexity is proportional to log N, where N is the number of free
151 blocks.
152 Address order first fit:
154 Strategy: Find the block with the lowest address satisfying the re‐
155 quested block size.
156 Implementation: A balanced binary search tree is used. The time
158 complexity is proportional to log N, where N is the number of free
159 blocks.
160 Address order first fit carrier best fit:
162 Strategy: Find the carrier with the lowest address that can satisfy
163 the requested block size, then find a block within that carrier us‐
164 ing the "best fit" strategy.
165 Implementation: Balanced binary search trees are used. The time
167 complexity is proportional to log N, where N is the number of free
168 blocks.
169 Address order first fit carrier address order best fit:
171 Strategy: Find the carrier with the lowest address that can satisfy
172 the requested block size, then find a block within that carrier us‐
173 ing the "address order best fit" strategy.
174 Implementation: Balanced binary search trees are used. The time
176 complexity is proportional to log N, where N is the number of free
177 blocks.
178 Age order first fit carrier address order first fit:
180 Strategy: Find the oldest carrier that can satisfy the requested
181 block size, then find a block within that carrier using the "ad‐
182 dress order first fit" strategy.
183 Implementation: A balanced binary search tree is used. The time
185 complexity is proportional to log N, where N is the number of free
186 blocks.
187 Age order first fit carrier best fit:
189 Strategy: Find the oldest carrier that can satisfy the requested
190 block size, then find a block within that carrier using the "best
191 fit" strategy.
192 Implementation: Balanced binary search trees are used. The time
194 complexity is proportional to log N, where N is the number of free
195 blocks.
196 Age order first fit carrier address order best fit:
198 Strategy: Find the oldest carrier that can satisfy the requested
199 block size, then find a block within that carrier using the "ad‐
200 dress order best fit" strategy.
201 Implementation: Balanced binary search trees are used. The time
203 complexity is proportional to log N, where N is the number of free
204 blocks.
205 Good fit:
207 Strategy: Try to find the best fit, but settle for the best fit
208 found during a limited search.
209 Implementation: The implementation uses segregated free lists with
211 a maximum block search depth (in each list) to find a good fit
212 fast. When the maximum block search depth is small (by default 3),
213 this implementation has a time complexity that is constant. The
214 maximum block search depth can be configured using parameter mbsd.
215 A fit:
217 Strategy: Do not search for a fit, inspect only one free block to
218 see if it satisfies the request. This strategy is only intended to
219 be used for temporary allocations.
220 Implementation: Inspect the first block in a free-list. If it sat‐
222 isfies the request, it is used, otherwise a new carrier is created.
223 The implementation has a time complexity that is constant.
224 As from ERTS 5.6.1 the emulator refuses to use this strategy on
226 other allocators than temp_alloc. This because it only causes prob‐
227 lems for other allocators.
228 Apart from the ordinary allocators described above, some pre-allocators
230 are used for some specific data types. These pre-allocators pre-allo‐
231 cate a fixed amount of memory for certain data types when the runtime
232 system starts. As long as pre-allocated memory is available, it is
233 used. When no pre-allocated memory is available, memory is allocated in
234 ordinary allocators. These pre-allocators are typically much faster
235 than the ordinary allocators, but can only satisfy a limited number of
236 requests.
237
239 Warning:
240 Only use these flags if you are sure what you are doing. Unsuitable
241 settings can cause serious performance degradation and even a system
242 crash at any time during operation.
243 Memory allocator system flags have the following syntax: +M<S><P> <V>,
246 where <S> is a letter identifying a subsystem, <P> is a parameter, and
247 <V> is the value to use. The flags can be passed to the Erlang emulator
248 (erl(1)) as command-line arguments.
249 System flags effecting specific allocators have an uppercase letter as
251 <S>. The following letters are used for the allocators:
252 * B: binary_alloc
254 * D: std_alloc
256 * E: ets_alloc
258 * F: fix_alloc
260 * H: eheap_alloc
262 * I: literal_alloc
264 * L: ll_alloc
266 * M: mseg_alloc
268 * R: driver_alloc
270 * S: sl_alloc
272 * T: temp_alloc
274 * X: exec_alloc
276 * Y: sys_alloc
278 Flags for Configuration of mseg_alloc
280 +MMamcbf <size>:
281 Absolute maximum cache bad fit (in kilobytes). A segment in the
282 memory segment cache is not reused if its size exceeds the re‐
283 quested size with more than the value of this parameter. Defaults
284 to 4096.
285 +MMrmcbf <ratio>:
287 Relative maximum cache bad fit (in percent). A segment in the mem‐
288 ory segment cache is not reused if its size exceeds the requested
289 size with more than relative maximum cache bad fit percent of the
290 requested size. Defaults to 20.
291 +MMsco true|false:
293 Sets super carrier only flag. Defaults to true. When a super car‐
294 rier is used and this flag is true, mseg_alloc only creates carri‐
295 ers in the super carrier. Notice that the alloc_util framework can
296 create sys_alloc carriers, so if you want all carriers to be cre‐
297 ated in the super carrier, you therefore want to disable use of
298 sys_alloc carriers by also passing +Musac false. When the flag is
299 false, mseg_alloc tries to create carriers outside of the super
300 carrier when the super carrier is full.
301 Note:
303 Setting this flag to false is not supported on all systems. The flag
304 is then ignored.
305 +MMscrfsd <amount>:
308 Sets super carrier reserved free segment descriptors. Defaults to
309 65536. This parameter determines the amount of memory to reserve
310 for free segment descriptors used by the super carrier. If the sys‐
311 tem runs out of reserved memory for free segment descriptors, other
312 memory is used. This can however cause fragmentation issues, so you
313 want to ensure that this never happens. The maximum amount of free
314 segment descriptors used can be retrieved from the erts_mmap tuple
315 part of the result from calling erlang:system_info({allocator,
316 mseg_alloc}).
317 +MMscrpm true|false:
319 Sets super carrier reserve physical memory flag. Defaults to true.
320 When this flag is true, physical memory is reserved for the whole
321 super carrier at once when it is created. The reservation is after
322 that left unchanged. When this flag is set to false, only virtual
323 address space is reserved for the super carrier upon creation. The
324 system attempts to reserve physical memory upon carrier creations
325 in the super carrier, and attempt to unreserve physical memory upon
326 carrier destructions in the super carrier.
327 Note:
329 What reservation of physical memory means, highly depends on the op‐
330 erating system, and how it is configured. For example, different mem‐
331 ory overcommit settings on Linux drastically change the behavior.
332 Setting this flag to false is possibly not supported on all systems.
334 The flag is then ignored.
335 +MMscs <size in MB>:
338 Sets super carrier size (in MB). Defaults to 0, that is, the super
339 carrier is by default disabled. The super carrier is a large con‐
340 tinuous area in the virtual address space. mseg_alloc always tries
341 to create new carriers in the super carrier if it exists. Notice
342 that the alloc_util framework can create sys_alloc carriers. For
343 more information, see +MMsco.
344 +MMmcs <amount>:
346 Maximum cached segments. The maximum number of memory segments
347 stored in the memory segment cache. Valid range is [0, 30]. De‐
348 faults to 10.
349 Flags for Configuration of sys_alloc
351 +MYe true:
352 Enables sys_alloc.
353 Note:
355 sys_alloc cannot be disabled.
356 +MYm libc:
359 malloc library to use. Only libc is available. libc enables the
360 standard libc malloc implementation. By default libc is used.
361 +MYtt <size>:
363 Trim threshold size (in kilobytes). This is the maximum amount of
364 free memory at the top of the heap (allocated by sbrk) that is kept
365 by malloc (not released to the operating system). When the amount
366 of free memory at the top of the heap exceeds the trim threshold,
367 malloc releases it (by calling sbrk). Trim threshold is specified
368 in kilobytes. Defaults to 128.
369 Note:
371 This flag has effect only when the emulator is linked with the GNU C
372 library, and uses its malloc implementation.
373 +MYtp <size>:
376 Top pad size (in kilobytes). This is the amount of extra memory
377 that is allocated by malloc when sbrk is called to get more memory
378 from the operating system. Defaults to 0.
379 Note:
381 This flag has effect only when the emulator is linked with the GNU C
382 library, and uses its malloc implementation.
383 Flags for Configuration of Allocators Based on alloc_util
386 If u is used as subsystem identifier (that is, <S> = u), all allocators
387 based on alloc_util are effected. If B, D, E, F, H, I, L, R, S, T, X is
388 used as subsystem identifier, only the specific allocator identifier is
389 effected.
390 +M<S>acul <utilization>|de:
392 Abandon carrier utilization limit. A valid <utilization> is an in‐
393 teger in the range [0, 100] representing utilization in percent.
394 When a utilization value > 0 is used, allocator instances are al‐
395 lowed to abandon multiblock carriers. If de (default enabled) is
396 passed instead of a <utilization>, a recommended non-zero utiliza‐
397 tion value is used. The value chosen depends on the allocator type
398 and can be changed between ERTS versions. Defaults to de, but this
399 can be changed in the future.
400 Carriers are abandoned when memory utilization in the allocator in‐
402 stance falls below the utilization value used. Once a carrier is
403 abandoned, no new allocations are made in it. When an allocator in‐
404 stance gets an increased multiblock carrier need, it first tries to
405 fetch an abandoned carrier from another allocator instance. If no
406 abandoned carrier can be fetched, it creates a new empty carrier.
407 When an abandoned carrier has been fetched, it will function as an
408 ordinary carrier. This feature has special requirements on the al‐
409 location strategy used. Only the strategies aoff, aoffcbf, aoff‐
410 caobf, ageffcaoffm, ageffcbf and ageffcaobf support abandoned car‐
411 riers.
412 This feature also requires multiple thread specific instances to be
414 enabled. When enabling this feature, multiple thread-specific in‐
415 stances are enabled if not already enabled, and the aoffcbf strat‐
416 egy is enabled if the current strategy does not support abandoned
417 carriers. This feature can be enabled on all allocators based on
418 the alloc_util framework, except temp_alloc (which would be point‐
419 less).
420 +M<S>acfml <bytes>:
422 Abandon carrier free block min limit. A valid <bytes> is a positive
423 integer representing a block size limit. The largest free block in
424 a carrier must be at least bytes large, for the carrier to be aban‐
425 doned. The default is zero but can be changed in the future.
426 See also acul.
428 +M<S>acnl <amount>:
430 Abandon carrier number limit. A valid <amount> is a positive inte‐
431 ger representing max number of abandoned carriers per allocator in‐
432 stance. Defaults to 1000 which will practically disable the limit,
433 but this can be changed in the future.
434 See also acul.
436 +M<S>as bf|aobf|aoff|aoffcbf|aoffcaobf|ageffcaoff|ageffcbf|ageff‐
438 caobf|gf|af:
439 Allocation strategy. The following strategies are valid:
440 * bf (best fit)
442 * aobf (address order best fit)
444 * aoff (address order first fit)
446 * aoffcbf (address order first fit carrier best fit)
448 * aoffcaobf (address order first fit carrier address order best
450 fit)
451 * ageffcaoff (age order first fit carrier address order first fit)
453 * ageffcbf (age order first fit carrier best fit)
455 * ageffcaobf (age order first fit carrier address order best fit)
457 * gf (good fit)
459 * af (a fit)
461 See the description of allocation strategies in section The al‐
463 loc_util Framework.
464 +M<S>asbcst <size>:
466 Absolute singleblock carrier shrink threshold (in kilobytes). When
467 a block located in an mseg_alloc singleblock carrier is shrunk, the
468 carrier is left unchanged if the amount of unused memory is less
469 than this threshold, otherwise the carrier is shrunk. See also rs‐
470 bcst.
471 +M<S>atags true|false:
473 Adds a small tag to each allocated block that contains basic infor‐
474 mation about what it is and who allocated it. Use the instrument
475 module to inspect this information.
476 The runtime overhead is one word per allocation when enabled. This
478 may change at any time in the future.
479 The default is true for binary_alloc and driver_alloc, and false
481 for the other allocator types.
482 +M<S>cg B|D|E|F|H||L|R|S|@|::
484 Set carrier pool to use for the allocator. Memory carriers will
485 only migrate between allocator instances that use the same carrier
486 pool. The following carrier pool names exist:
487 B:
489 Carrier pool associated with binary_alloc.
490 D:
492 Carrier pool associated with std_alloc.
493 E:
495 Carrier pool associated with ets_alloc.
496 F:
498 Carrier pool associated with fix_alloc.
499 H:
501 Carrier pool associated with eheap_alloc.
502 L:
504 Carrier pool associated with ll_alloc.
505 R:
507 Carrier pool associated with driver_alloc.
508 S:
510 Carrier pool associated with sl_alloc.
511 @:
513 Carrier pool associated with the system as a whole.
514 Besides passing carrier pool name as value to the parameter, you
516 can also pass :. By passing : instead of carrier pool name, the al‐
517 locator will use the carrier pool associated with itself. By pass‐
518 ing the command line argument "+Mucg :", all allocators that have
519 an associated carrier pool will use the carrier pool associated
520 with themselves.
521 The association between carrier pool and allocator is very loose.
523 The associations are more or less only there to get names for the
524 amount of carrier pools needed and names of carrier pools that can
525 be easily identified by the : value.
526 This flag is only valid for allocators that have an associated car‐
528 rier pool. Besides that, there are no restrictions on carrier pools
529 to use for an allocator.
530 Currently the @ carrier pool is used by default, but this will most
532 likely change.
533 +M<S>e true|false:
535 Enables allocator <S>.
536 +M<S>lmbcs <size>:
538 Largest (mseg_alloc) multiblock carrier size (in kilobytes). See
539 the description on how sizes for mseg_alloc multiblock carriers are
540 decided in section The alloc_util Framework. On 32-bit Unix style
541 OS this limit cannot be set > 64 MB.
542 +M<S>mbcgs <ratio>:
544 (mseg_alloc) multiblock carrier growth stages. See the description
545 on how sizes for mseg_alloc multiblock carriers are decided in sec‐
546 tion The alloc_util Framework.
547 +M<S>mbsd <depth>:
549 Maximum block search depth. This flag has effect only if the good
550 fit strategy is selected for allocator <S>. When the good fit
551 strategy is used, free blocks are placed in segregated free-lists.
552 Each free-list contains blocks of sizes in a specific range. The
553 maxiumum block search depth sets a limit on the maximum number of
554 blocks to inspect in a free-list during a search for suitable block
555 satisfying the request.
556 +M<S>mmbcs <size>:
558 Main multiblock carrier size. Sets the size of the main multiblock
559 carrier for allocator <S>. The main multiblock carrier is allocated
560 through sys_alloc and is never deallocated.
561 +M<S>mmmbc <amount>:
563 Maximum mseg_alloc multiblock carriers. Maximum number of multi‐
564 block carriers allocated through mseg_alloc by allocator <S>. When
565 this limit is reached, new multiblock carriers are allocated
566 through sys_alloc.
567 +M<S>mmsbc <amount>:
569 Maximum mseg_alloc singleblock carriers. Maximum number of single‐
570 block carriers allocated through mseg_alloc by allocator <S>. When
571 this limit is reached, new singleblock carriers are allocated
572 through sys_alloc.
573 +M<S>ramv <bool>:
575 Realloc always moves. When enabled, reallocate operations are more
576 or less translated into an allocate, copy, free sequence. This of‐
577 ten reduces memory fragmentation, but costs performance.
578 +M<S>rmbcmt <ratio>:
580 Relative multiblock carrier move threshold (in percent). When a
581 block located in a multiblock carrier is shrunk, the block is moved
582 if the ratio of the size of the returned memory compared to the
583 previous size is more than this threshold, otherwise the block is
584 shrunk at the current location.
585 +M<S>rsbcmt <ratio>:
587 Relative singleblock carrier move threshold (in percent). When a
588 block located in a singleblock carrier is shrunk to a size smaller
589 than the value of parameter sbct, the block is left unchanged in
590 the singleblock carrier if the ratio of unused memory is less than
591 this threshold, otherwise it is moved into a multiblock carrier.
592 +M<S>rsbcst <ratio>:
594 Relative singleblock carrier shrink threshold (in percent). When a
595 block located in an mseg_alloc singleblock carrier is shrunk, the
596 carrier is left unchanged if the ratio of unused memory is less
597 than this threshold, otherwise the carrier is shrunk. See also as‐
598 bcst.
599 +M<S>sbct <size>:
601 Singleblock carrier threshold (in kilobytes). Blocks larger than
602 this threshold are placed in singleblock carriers. Blocks smaller
603 than this threshold are placed in multiblock carriers. On 32-bit
604 Unix style OS this threshold cannot be set > 8 MB.
605 +M<S>smbcs <size>:
607 Smallest (mseg_alloc) multiblock carrier size (in kilobytes). See
608 the description on how sizes for mseg_alloc multiblock carriers are
609 decided in section The alloc_util Framework.
610 +M<S>t true|false:
612 Multiple, thread-specific instances of the allocator. This option
613 has only effect on the runtime system with SMP support. Default be‐
614 havior on the runtime system with SMP support is NoSchedulers+1 in‐
615 stances. Each scheduler uses a lock-free instance of its own and
616 other threads use a common instance.
617 Before ERTS 5.9 it was possible to configure a smaller number of
619 thread-specific instances than schedulers. This is, however, not
620 possible anymore.
621 Flags for Configuration of alloc_util
623 All allocators based on alloc_util are effected.
624 +Muycs <size>:
626 sys_alloc carrier size. Carriers allocated through sys_alloc are
627 allocated in sizes that are multiples of the sys_alloc carrier
628 size. This is not true for main multiblock carriers and carriers
629 allocated during a memory shortage, though.
630 +Mummc <amount>:
632 Maximum mseg_alloc carriers. Maximum number of carriers placed in
633 separate memory segments. When this limit is reached, new carriers
634 are placed in memory retrieved from sys_alloc.
635 +Musac <bool>:
637 Allow sys_alloc carriers. Defaults to true. If set to false,
638 sys_alloc carriers are never created by allocators using the al‐
639 loc_util framework.
640 Special Flag for literal_alloc
642 +MIscs <size in MB>:
643 literal_alloc super carrier size (in MB). The amount of virtual ad‐
644 dress space reserved for literal terms in Erlang code on 64-bit ar‐
645 chitectures. Defaults to 1024 (that is, 1 GB), which is usually
646 sufficient. The flag is ignored on 32-bit architectures.
647 Instrumentation Flags
649 +M<S>atags:
650 Adds a small tag to each allocated block that contains basic infor‐
651 mation about what it is and who allocated it. See +M<S>atags for a
652 more complete description.
653 +Mit X:
655 Reserved for future use. Do not use this flag.
656 Note:
658 When instrumentation of the emulator is enabled, the emulator uses more
659 memory and runs slower.
660 Other Flags
663 +Mea min|max|r9c|r10b|r11b|config:
664 Options:
665 min:
667 Disables all allocators that can be disabled.
668 max:
670 Enables all allocators (default).
671 r9c|r10b|r11b:
673 Configures all allocators as they were configured in respective
674 Erlang/OTP release. These will eventually be removed.
675 config:
677 Disables features that cannot be enabled while creating an allo‐
678 cator configuration with erts_alloc_config(3).
679 Note:
681 This option is to be used only while running erts_alloc_config(3),
682 not when using the created configuration.
683 +Mlpm all|no:
686 Lock physical memory. Defaults to no, that is, no physical memory
687 is locked. If set to all, all memory mappings made by the runtime
688 system are locked into physical memory. If set to all, the runtime
689 system fails to start if this feature is not supported, the user
690 has not got enough privileges, or the user is not allowed to lock
691 enough physical memory. The runtime system also fails with an out
692 of memory condition if the user limit on the amount of locked mem‐
693 ory is reached.
694
696 Only some default values have been presented here. For information
697 about the currently used settings and the current status of the alloca‐
698 tors, see erlang:system_info(allocator) and erlang:system_info({alloca‐
699 tor, Alloc}).
700 Note:
702 Most of these flags are highly implementation-dependent and can be
703 changed or removed without prior notice.
704 erts_alloc is not obliged to strictly use the settings that have been
706 passed to it (it can even ignore them).
707 The erts_alloc_config(3) tool can be used to aid creation of an
710 erts_alloc configuration that is suitable for a limited number of run‐
711 time scenarios.
712
714 erl(1), erlang(3), erts_alloc_config(3), instrument(3)
715Ericsson AB erts 11.2.2.2 erts_alloc(3)