Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!sdd.hp.com!cs.utexas.edu!uunet!overload!dillon
From: dillon@overload.Berkeley.CA.US (Matthew Dillon)
Newsgroups: comp.sys.amiga.programmer
Subject: Re:  free() in SAS C
Message-ID: <dillon.7413@overload.Berkeley.CA.US>
Date: 7 May 91 20:56:51 GMT
References: <1991May02.143148.22732@edb.tih.no> <MWM.91May6120013@raven.pa.dec.com>
Distribution: comp
Organization: Not an Organization
Lines: 52

In article <MWM.91May6120013@raven.pa.dec.com> mwm@pa.dec.com (Mike (My Watch Has Windows) Meyer) writes:
>In article <dillon.7247@overload.Berkeley.CA.US> dillon@overload.Berkeley.CA.US (Matthew Dillon) writes:
>   >If you're doing lots of frees/allocs later on, you'll take a
>   >performance hit.
>   >
>   >	<mike
>
>	Actually, AllocMem & FreeMem are *faster* than SAS/C's
>	malloc & free.	The only loose is that your system is more
>	susceptible to fragmentation.
>
>Matt,
>
>I did some tests on 1.3, doing lots of small mallocs/frees vs. doing
>lots of AllocMem/FreeMems. Malloc/free was _much_ faster. The critical
>condition is that you're reusing space, and not getting new space from
>the system. If you're not reusing the space, then AllocMem & FreeMem
>will be faster.
>
>If you're going to do a bunch of allocations, then a bunch of frees, a
>single AllocEntry (I think that's the name I want) call is probably
>fastest.
>
>	<mike

    In the experiments I had made, AllocMem() was faster, it was
    FreeMem() that was slower.  At least under 2.0 ...  I suppose
    the speed depends on the overall fragmentation of system memory,
    something that does not effect Allocate() on a private memory
    pool.

    As far as allocating lots of like-sized structures, I don't use
    malloc() *or* AllocMem().  That is, I use one of the two to allocate
    a large block, and then allocate the like-sized structures out of
    the block manually.  In this case freeing is accomplished by simply
    adding the structure to a freelist.  The result goes an order of
    magnitude faster than malloc()/free() OR AllocMem()/FreeMem().

				    -Matt

>--
>Cheeseburger in paradise				Mike Meyer
>Making the best of every virtue and vice		mwm@pa.dec.com
>Worth every damn bit of sacrifice			decwrl!mwm
>To get a cheeseburger in paradise

--

    Matthew Dillon	    dillon@Overload.Berkeley.CA.US
    891 Regal Rd.	    uunet.uu.net!overload!dillon
    Berkeley, Ca. 94708
    USA