[niemeyer@conectiva.com: Re: [Python-Dev] Python's footprint]

[Gustavo Niemeyer]

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Hi Martin!

> > Now that 2.2 is history (well, kind of ;-), would it be the time to
> > think about this again?
>=20
> By "consideration early in 2.3's life cycle", the OP probably meant
> that a patch should be posted to SF. Are you willing to implement the
> complete change (i.e. create a patch that changes each and every
> source file)? If so, please post one to SF. You may want to start this
> slowly, first creating only the infrastructure and touching a single
> file (say, stringobject.c)

Yes, I'm going to implement it. I'd just like to know if there was
interest in the patch. Implementing it slowly looks like a nice idea
as well. I'll post a patch there. Thanks!

> I'd personally like to see opportunities for more magic used. E.g. in
> a compiler that uses sections, putting all doc strings into a single
> section might be desirable. They will be a contiguous fragment of the
> python executable, which helps on demand-paged systems to reduce the
> startup time. Going further, it might be possible to strip off "unused
> sections" from the binary after it has been linked, deferring the
> choice of doc string presence to the installation time.

Interesting.

I know it's possible to discard a session. OTOH, I don't know what happens
if somebody refer to discarded data. I'll have a look at this.

> For that to work, we'd first need to know what compilers offer what
> syntax to implement such magic, then generalize it to the right macro.
> If that is a desirable goal, I'd be willing to investigate how to
> achieve things with gcc, on ELF systems.

This is something pretty easy with gcc. When reading your email, I
remembered that the kernel uses this magic to discard a session with
code used just when initializing. Looking in the kernel code, I found
out this in include/linux/init.h:

/*
 * Mark functions and data as being only used at initialization
 * or exit time.
 */
#define __init      __attribute__ ((__section__ (".text.init")))
#define __exit      __attribute__ ((unused, __section__(".text.exit")))
#define __initdata  __attribute__ ((__section__ (".data.init")))
#define __exitdata  __attribute__ ((unused, __section__ (".data.exit")))
#define __initsetup __attribute__ ((unused,__section__ (".setup.init")))
#define __init_call __attribute__ ((unused,__section__ (".initcall.init")))
#define __exit_call __attribute__ ((unused,__section__ (".exitcall.exit")))

After surrounding doc strings with a macro, this will be easy to achieve.

Thanks!

--=20
Gustavo Niemeyer

[ 2AAC 7928 0FBF 0299 5EB5  60E2 2253 B29A 6664 3A0C ]

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