From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Dmitry Antipov <dmantipov@yandex.ru>
Cc: emacs-devel@gnu.org
Subject: Re: Proposal: block-based vector allocator
Date: Wed, 06 Jun 2012 09:13:07 -0400 [thread overview]
Message-ID: <jwvfwa8k3d3.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <4FCF007F.7080104@yandex.ru> (Dmitry Antipov's message of "Wed, 06 Jun 2012 11:02:23 +0400")
>> BTW, if we change the vector allocation so it only uses vector-blocks
>> for vectors smaller than "vector-block-size / 2", as I think we should,
> Why?
I explained this earlier: using a vector-block for largish vectors is
not efficient (because the overhead of the vector-block is not shared
among enough vectors).
E.g. for a vector of size VECTOR_BLOCK_BYTES, using the vector-block
code is a complete waste .
> Whatever this limit's value, it's possible to construct an allocation
> pattern which will be a worst-case for this allocator, and I don't see
> why one specially designed worst-case is more probabilistic than another.
For the case of a vector of size VECTOR_BLOCK_BYTES, allocating in
a vector block will always be a bad idea, no matter the scenario.
Now obviously, this is not true of all vector sizes, and I don't know
where's the threshold where we should switch from one to the other, but
vector-block-size / 2 sounds like a safe choice (even if the threshold
is not quite there, there's probably not much to gain from being
closer).
>> I'm not saying the code is wrong. I'm saying that its correctness
>> should be made more explicit by using a different MEM_TYPE for
>> vector blocks. This way the correctness argument is trivial rather than
>> relying on some reasoning about which kind of vector allocation
>> is used in which circumstance.
> Yet another mem_type duplicates live_vector_p,
I don't see why that should be the case.
Stefan
next prev parent reply other threads:[~2012-06-06 13:13 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-06 5:22 Proposal: block-based vector allocator Dmitry Antipov
2011-12-06 13:35 ` Stefan Monnier
2011-12-06 15:14 ` Dmitry Antipov
2011-12-06 19:39 ` Stefan Monnier
2011-12-07 5:05 ` Dmitry Antipov
2011-12-07 12:27 ` Carsten Mattner
2011-12-07 13:52 ` Stefan Monnier
2011-12-07 16:08 ` Dmitry Antipov
2011-12-07 16:30 ` Stefan Monnier
2011-12-08 8:50 ` Dmitry Antipov
2011-12-08 13:52 ` Stefan Monnier
2011-12-08 1:53 ` Stephen J. Turnbull
2011-12-08 4:41 ` Dmitry Antipov
2011-12-08 14:10 ` Stefan Monnier
2011-12-08 16:48 ` Dmitry Antipov
2011-12-08 19:58 ` Stefan Monnier
2011-12-09 7:32 ` Eli Zaretskii
2011-12-09 9:04 ` Dmitry Antipov
2011-12-09 14:05 ` Stefan Monnier
2011-12-09 16:15 ` Dmitry Antipov
2011-12-09 21:04 ` Stefan Monnier
2011-12-11 13:18 ` Dmitry Antipov
2011-12-12 3:07 ` Dmitry Antipov
2011-12-12 16:24 ` Stefan Monnier
2011-12-09 4:44 ` Stephen J. Turnbull
[not found] ` <jwvaa1yjs21.fsf-monnier+emacs@gnu.org>
2012-05-17 7:58 ` Dmitry Antipov
2012-05-18 17:40 ` Stefan Monnier
2012-05-21 12:19 ` Dmitry Antipov
2012-05-21 13:02 ` Andreas Schwab
2012-05-21 13:48 ` Dmitry Antipov
2012-05-21 15:07 ` Andreas Schwab
2012-05-22 5:23 ` Ken Raeburn
2012-05-21 20:12 ` Stefan Monnier
2012-05-22 8:24 ` Dmitry Antipov
2012-05-31 13:44 ` Dmitry Antipov
2012-05-31 15:43 ` Paul Eggert
2012-06-01 5:15 ` Dmitry Antipov
2012-06-01 5:44 ` Paul Eggert
2012-06-01 9:06 ` Dmitry Antipov
2012-06-01 17:36 ` Stefan Monnier
2012-06-02 0:32 ` Paul Eggert
2012-06-02 7:41 ` Eli Zaretskii
2012-06-03 6:49 ` Paul Eggert
2012-06-03 14:26 ` Eli Zaretskii
2012-05-31 21:16 ` Stefan Monnier
2012-06-01 7:34 ` Dmitry Antipov
2012-06-01 17:40 ` Stefan Monnier
2012-06-01 17:43 ` Stefan Monnier
2012-06-06 7:02 ` Dmitry Antipov
2012-06-06 13:13 ` Stefan Monnier [this message]
2012-06-06 14:58 ` Dmitry Antipov
2012-06-06 19:18 ` Stefan Monnier
2012-06-07 10:03 ` Dmitry Antipov
2012-06-07 14:07 ` Stefan Monnier
2012-06-08 5:50 ` Dmitry Antipov
2012-06-08 6:17 ` Stefan Monnier
2012-06-08 8:49 ` Dmitry Antipov
2012-06-08 8:53 ` Eli Zaretskii
2012-06-08 9:41 ` Eli Zaretskii
2012-06-08 10:00 ` Eli Zaretskii
2012-06-08 6:57 ` Eli Zaretskii
2012-06-08 6:38 ` Paul Eggert
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