[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Enlarge MAX_ALLOCA?
From: |
Stefan Monnier |
Subject: |
Re: Enlarge MAX_ALLOCA? |
Date: |
Thu, 19 Jun 2014 14:28:08 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.4.50 (gnu/linux) |
> Does anyone see problems with the change below, which raises the bar
> for 'alloca' to 64KB? Are there any systems out there that we care
> about whose stack is so small as to make this dangerous?
It makes the potential max increment of stack space "per
lisp-eval-depth" larger, and hence increases the risk that we'll eat up
our stack before we bump into max-lisp-eval-depth.
The idea behind the 16KB limit is that the cost of malloc+free is likely
to be negligible compared the filling and using 16KB of data.
> Why 64KB? Because that's the size of the work area coding.c allocates
> whenever it needs to encode or decode something. It turns out we do
> this a lot, e.g., every redisplay calls file-readable-p on the icon
> image files, which needs to encode the file name. While the work area
> is immediately free'd, I think allocating such a large buffer so much
> has a potential of creating an unnecessary memory pressure on 'malloc',
> and perhaps cause excess fragmentation and/or enlarge memory footprint
> in some cases.
I think it makes a lot of sense to try and allocate this space on the
stack when decoding file names, but why does it allocate such a huge
buffer just to en/decode a puny file name?
If the malloc/free done for this encode/decode is relatively costly,
maybe it's because we allocate too much space compared to what we use.
Stefan
- Re: Enlarge MAX_ALLOCA?, (continued)
Re: Enlarge MAX_ALLOCA?, Stefan Monnier, 2014/06/19
Re: Enlarge MAX_ALLOCA?, Dmitry Antipov, 2014/06/20
Re: Enlarge MAX_ALLOCA?, Eli Zaretskii, 2014/06/20
Re: Enlarge MAX_ALLOCA?, Andreas Schwab, 2014/06/20
Re: Enlarge MAX_ALLOCA?, David Kastrup, 2014/06/20
Re: Enlarge MAX_ALLOCA?,
Stefan Monnier <=
- Re: Enlarge MAX_ALLOCA?, Eli Zaretskii, 2014/06/19
- Re: Enlarge MAX_ALLOCA?, Stefan Monnier, 2014/06/19
- Re: Enlarge MAX_ALLOCA?, Eli Zaretskii, 2014/06/20
- Re: Enlarge MAX_ALLOCA?, Stefan Monnier, 2014/06/20
- Re: Enlarge MAX_ALLOCA?, Eli Zaretskii, 2014/06/20
- Re: Enlarge MAX_ALLOCA?, Stefan Monnier, 2014/06/20
- Re: Enlarge MAX_ALLOCA?, Eli Zaretskii, 2014/06/20
- RE: Enlarge MAX_ALLOCA?, Herring, Davis, 2014/06/20
- Re: Enlarge MAX_ALLOCA?, Dmitry Antipov, 2014/06/20
- Re: Enlarge MAX_ALLOCA?, Eli Zaretskii, 2014/06/20