[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH] Efficient Gensym Hack
From: |
Ludovic Courtès |
Subject: |
Re: [PATCH] Efficient Gensym Hack |
Date: |
Sat, 10 Mar 2012 23:55:59 +0100 |
User-agent: |
Gnus/5.110018 (No Gnus v0.18) Emacs/24.0.93 (gnu/linux) |
Hi Mark,
Just a few questions.
Mark H Weaver <address@hidden> skribis:
> Here's an implementation of the efficient gensym hack for stable-2.0.
> It makes 'gensym' about 4.7 times faster on my Yeeloong. Gensyms are
> not given names or even numbers until they are asked for their names or
> hash values (for 'equal?' hash tables only).
Ooooh, I only really understood when seeing this:
+ return scm_double_cell (scm_tc7_symbol | SCM_I_F_SYMBOL_LAZY_GENSYM,
+ SCM_UNPACK (prefix_stringbuf), (scm_t_bits) 0,
+ SCM_UNPACK (scm_cons (SCM_BOOL_F, SCM_EOL)));
So you can actually ‘eq?’ or ‘hashq’ them regardless of whether they
have a name, nice! :-)
> The first patch adds an optimization for strings that is important for
> gensyms. It avoids locking a mutex when setting the shared flag on a
> stringbuf if the shared flag is already set.
How much impact does this have? Thanks to futexes, mutex_lock should be
fairly cheap when there’s no contention, no?
Nice work!
Thanks,
Ludo’.
Re: [PATCH] Efficient Gensym Hack,
Ludovic Courtès <=