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* bug#48264: 28.0.50; Changing the default for DEFVAR_PER_BUFFER variables takes O(#buffers) time
@ 2021-05-06 20:24 Spencer Baugh
  2021-05-06 21:33 ` bug#48264: [PATCH v3 00/15] Speeding up setting the default for DEFVAR_PER_BUFFER vars Spencer Baugh
                   ` (15 more replies)
  0 siblings, 16 replies; 84+ messages in thread
From: Spencer Baugh @ 2021-05-06 20:24 UTC (permalink / raw)
  To: 48264


When changing the default for a Lisp variable defined in the C source
with the DEFVAR_PER_BUFFER macro, whether by let or by set-default, it
takes time proportional to the number of currently live buffers.

Note, DEFVAR_PER_BUFFER variables are stored as Lisp_Object fields in
struct buffer.

The cause of the pathological performance is that setting a default for
a DEFVAR_PER_BUFFER variable iterates over every struct buffer (that
doesn't already have a binding) to set the field corresponding to the
variable.

This is because accessing a DEFVAR_PER_BUFFER variable is done purely by
looking at the current buffer, even if the buffer doesn't have a local
binding for the variable.

This issue was previously reported in bug#41029 and noticed as part of
several other bugs.

I have a patch series which fixes this issue by making DEFVAR_PER_BUFFER
variable accesses fall back to the default if there's no local binding
for the variable, which I'll send shortly as a followup.






^ permalink raw reply	[flat|nested] 84+ messages in thread

end of thread, other threads:[~2022-08-02 11:11 UTC | newest]

Thread overview: 84+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2021-05-06 20:24 bug#48264: 28.0.50; Changing the default for DEFVAR_PER_BUFFER variables takes O(#buffers) time Spencer Baugh
2021-05-06 21:33 ` bug#48264: [PATCH v3 00/15] Speeding up setting the default for DEFVAR_PER_BUFFER vars Spencer Baugh
2021-05-07 11:05   ` Eli Zaretskii
2021-05-08  2:08   ` bug#48264: [PATCH v4 " Spencer Baugh
2021-05-08  2:08     ` Spencer Baugh
2021-05-08  2:08     ` bug#48264: [PATCH v4 01/14] Stop checking the constant default for enable_multibyte_characters Spencer Baugh
2021-05-08  2:08     ` bug#48264: [PATCH v4 02/14] Take offset not idx in PER_BUFFER_VALUE_P Spencer Baugh
2021-05-08  2:08     ` bug#48264: [PATCH v4 03/14] Add and use BVAR_HAS_DEFAULT_VALUE_P Spencer Baugh
2021-05-08  2:08     ` bug#48264: [PATCH v4 04/14] Combine unnecessarily separate loops in buffer.c Spencer Baugh
2021-05-08  2:08     ` bug#48264: [PATCH v4 05/14] Add and use KILL_PER_BUFFER_VALUE Spencer Baugh
2021-05-08  2:08     ` bug#48264: [PATCH v4 06/14] Rearrange set_internal for buffer forwarded symbols Spencer Baugh
2021-05-08  2:08     ` bug#48264: [PATCH v4 07/14] Use BVAR_OR_DEFAULT for per-buffer vars with defaults Spencer Baugh
2021-05-08  2:08     ` bug#48264: [PATCH v4 08/14] Remove unnecessary Qunbound check Spencer Baugh
2021-05-08  2:09     ` bug#48264: [PATCH v4 09/14] Get rid of buffer_permanent_local_flags array Spencer Baugh
2021-05-08  2:09     ` bug#48264: [PATCH v4 10/14] Delete SET_PER_BUFFER_VALUE_P and buffer local_flags field Spencer Baugh
2021-05-08  2:09     ` bug#48264: [PATCH v4 11/14] Set buffer_defaults fields without a default to Qunbound Spencer Baugh
2021-05-08  2:09     ` bug#48264: [PATCH v4 12/14] Assert that PER_BUFFER_IDX for Lisp variables is not 0 Spencer Baugh
2021-05-08  2:09     ` bug#48264: [PATCH v4 13/14] Remove PER_BUFFER_IDX and buffer_local_flags Spencer Baugh
2021-05-08  2:09     ` bug#48264: [PATCH v4 14/14] Add and use BVAR_FIELD macros Spencer Baugh
2021-05-08 18:06     ` bug#48264: [PATCH v4 00/15] Speeding up setting the default for DEFVAR_PER_BUFFER vars Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-05-06 21:33 ` bug#48264: [PATCH v3 01/15] Stop checking the constant default for enable_multibyte_characters Spencer Baugh
2021-05-06 21:33 ` bug#48264: [PATCH v3 02/15] Take offset not idx in PER_BUFFER_VALUE_P Spencer Baugh
2021-05-07  7:27   ` Eli Zaretskii
2021-05-07 12:45     ` Spencer Baugh
2021-05-07 12:54       ` Eli Zaretskii
2021-05-06 21:33 ` bug#48264: [PATCH v3 03/15] Add and use BUFFER_DEFAULT_VALUE_P Spencer Baugh
2021-05-07  7:29   ` Eli Zaretskii
2021-05-07 12:49     ` Spencer Baugh
2021-05-07 12:58       ` Eli Zaretskii
2021-05-07 13:38         ` Spencer Baugh
2021-05-07 13:42           ` Eli Zaretskii
2021-05-07 14:30             ` Spencer Baugh
2021-05-07 14:39               ` Eli Zaretskii
2021-05-06 21:33 ` bug#48264: [PATCH v3 04/15] Combine unnecessarily separate loops in buffer.c Spencer Baugh
2021-05-06 21:33 ` bug#48264: [PATCH v3 05/15] Add and use KILL_PER_BUFFER_VALUE Spencer Baugh
2021-05-06 21:33 ` bug#48264: [PATCH v3 06/15] Rearrange set_internal for buffer forwarded symbols Spencer Baugh
2021-05-07 10:45   ` Eli Zaretskii
2021-05-07 14:26     ` Spencer Baugh
2021-05-06 21:33 ` bug#48264: [PATCH v3 07/15] Add BVAR_OR_DEFAULT macro as a stub Spencer Baugh
2021-05-07 10:54   ` Eli Zaretskii
2021-05-07 13:05     ` Spencer Baugh
2021-05-07 13:12       ` Eli Zaretskii
2021-05-07 13:24         ` Spencer Baugh
2021-05-07 13:32           ` Eli Zaretskii
2021-05-06 21:33 ` bug#48264: [PATCH v3 08/15] Set non-buffer-local BVARs to Qunbound Spencer Baugh
2021-05-07 10:37   ` Eli Zaretskii
2021-05-07 12:54     ` Spencer Baugh
2021-05-07 13:00       ` Eli Zaretskii
2021-05-06 21:33 ` bug#48264: [PATCH v3 09/15] Remove unnecessary Qunbound check Spencer Baugh
2021-05-06 21:33 ` bug#48264: [PATCH v3 10/15] Get rid of buffer_permanent_local_flags array Spencer Baugh
2021-05-06 21:33 ` bug#48264: [PATCH v3 11/15] Delete SET_PER_BUFFER_VALUE_P and buffer local_flags field Spencer Baugh
2021-05-06 21:33 ` bug#48264: [PATCH v3 12/15] Set buffer_defaults fields without a default to Qunbound Spencer Baugh
2021-05-07 10:42   ` Eli Zaretskii
2021-05-07 13:20     ` Spencer Baugh
2021-05-07 13:29       ` Eli Zaretskii
2021-05-07 14:15         ` Spencer Baugh
2021-05-07 14:30           ` Eli Zaretskii
2021-05-07 21:35             ` Spencer Baugh
2021-05-08  6:40               ` Eli Zaretskii
2021-05-08 13:22                 ` Spencer Baugh
2021-05-06 21:33 ` bug#48264: [PATCH v3 13/15] Assert that PER_BUFFER_IDX for Lisp variables is not 0 Spencer Baugh
2021-05-06 21:33 ` bug#48264: [PATCH v3 14/15] Remove PER_BUFFER_IDX and buffer_local_flags Spencer Baugh
2021-05-06 21:33 ` bug#48264: [PATCH v3 15/15] Add and use BVAR_FIELD macros Spencer Baugh
2021-05-07 11:03   ` Eli Zaretskii
2021-05-07 12:59     ` Spencer Baugh
2021-05-07 13:08       ` Eli Zaretskii
2021-05-07 21:43         ` Spencer Baugh
2021-05-08  6:55           ` Eli Zaretskii
2021-05-08 13:35             ` Spencer Baugh
2021-05-08 13:58               ` Eli Zaretskii
2021-05-08 17:13                 ` Spencer Baugh
2021-05-08 19:03                 ` Spencer Baugh
2021-05-09  8:10                   ` Eli Zaretskii
2021-05-09 17:09                     ` Spencer Baugh
2021-05-09 17:09                       ` bug#48264: [PATCH 1/2] Take buffer field name in DEFVAR_PER_BUFFER Spencer Baugh
2021-05-09 17:09                       ` bug#48264: [PATCH 2/2] Add compile-time check that BVAR is used correctly Spencer Baugh
2021-05-09 18:09                         ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-05-09 18:29                           ` Eli Zaretskii
2021-05-10 14:09                             ` Spencer Baugh
2022-07-01 12:18                               ` bug#48264: 28.0.50; Changing the default for DEFVAR_PER_BUFFER variables takes O(#buffers) time Lars Ingebrigtsen
2022-07-01 18:49                                 ` Spencer Baugh
2022-07-02 12:00                                   ` Lars Ingebrigtsen
2022-08-02 11:11                                     ` Lars Ingebrigtsen
2021-05-09 10:08                 ` bug#48264: [PATCH v3 15/15] Add and use BVAR_FIELD macros Lars Ingebrigtsen

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