Re: [Sbcl-help] Very slow and consy sb-alien:deref

[Christophe R. <cs...@ca...>]

Dave Roberts <ld...@dr...> writes:

> * buffer
>
> #<SB-ALIEN-INTERNALS:ALIEN-VALUE :SAP #X08274C20 :TYPE (* (UNSIGNED 8))>
> * (time (deref buffer 12))
>
> Evaluation took:
>   		 0.006 seconds of real time
>   		 0.0 seconds of user run time
>   		 0.0 seconds of system run time
>   		 0 page faults and
>   		 94224 bytes consed.

As a general rule, measuring something with just one call is a poor
way of getting accurate readings.  Also, you should take care to
measure what you actually want to know about -- not included in your
timings above are the amount of time it took you to type that form
into the REPL.  (If you think that's needlessly pedantic, consider the
possibility that the compiler can do work behind-the-scenes that it
can't if you just interact with top-level forms in the REPL -- and
that typically your program is compiled.)

Without knowing the details, it's hard to tell exactly what is going
on.  Could you post a more complete transcript, including your
definition of buffer?

Cheers,

Christophe
-- 
http://www-jcsu.jesus.cam.ac.uk/~csr21/       +44 1223 510 299/+44 7729 383 757
(set-pprint-dispatch 'number (lambda (s o) (declare (special b)) (format s b)))
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