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| From | "BartC" <bc@freeuk.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Malloc Query |
| Date | 2011-05-18 22:31 +0100 |
| Organization | A noiseless patient Spider |
| Message-ID | <ir1dto$6en$1@dont-email.me> (permalink) |
| References | <iquit3$pl$1@speranza.aioe.org> <87aael3xw1.fsf@blp.benpfaff.org><ir096a$6vd$1@dont-email.me> <0.9e954b297cf63735a997.20110518193428BST.87zkmjuabv.fsf@bsb.me.uk> |
"Ben Bacarisse" <ben.usenet@bsb.me.uk> wrote in message
news:0.9e954b297cf63735a997.20110518193428BST.87zkmjuabv.fsf@bsb.me.uk...
> "BartC" <bc@freeuk.com> writes:
>
>> "Ben Pfaff" <blp@cs.stanford.edu> wrote in message
>> news:87aael3xw1.fsf@blp.benpfaff.org...
> <snip>
>>> According to an academic study I read some time ago, there is
>>> rarely any significant advantage to special-purpose memory
>>> allocators. In a quick online search, I didn't find a reference
>>> to this paper, but perhaps someone else here has a copy of it.
>>
>> I've just done a test where allocating and freeing large numbers of
>> 4-byte blocks took twenty times longer using malloc/free (and probably
>> took 2-4
>> times as much space) than using a special allocator.
>
> That's interesting, but of limited value unless you can give more
> details. Ideally, can you post the code? That way it can tried on
> different systems with different C libraries.
Nothing special, just a contrived example of a special allocator, in this
case (since I was short of time) just linearly allocating 100,000 ints one
after another, then freeing them in the same order. Nevertheless, malloc
took much longer. The code I used is given below (actually it wasn't written
in C that's why it's 1-based).
> At least say what the "special allocator" is. Relative speed up must be
> relative to something known, not something mysterious.
>
>> How significant this is depends on the application, but I don't think
>> you can just dismiss such an allocator.
>
> But no one else can consider it either since we don't know what it is.
It depends on how much of an application is spent on these special
allocations. (In my code, I use special allocators for sizes up to 1KB, and
malloc/free beyond that.)
#include <stdio.h>
#include <stdlib.h>
/* Use 1 for malloc/free, or 0 for the simple allocator used here */
#define USEMALLOC 1
#define maxsize 100000
int data[maxsize+1];
int* freelist=0;
int dataindex=0;
int* allocint(void){
int *p;
#if USEMALLOC
return malloc(sizeof (int));
#endif
if (freelist) {
p=freelist;
freelist=(int*)*freelist;
return p;
}
if (dataindex>=maxsize) {
puts("Out of memory");
exit(0);
}
return &data[++dataindex];
}
void freeint(int* p){
#if USEMALLOC
free(p);
return;
#endif
*p=(int)freelist;
freelist=p;
}
int main(void){
int a=0;
int i,n;
for (n=1; n<=100; ++n) {
for (i=1; i<=maxsize; ++i)
allocint();
for (i=1; i<=maxsize; ++i)
freeint(&data[i]);
}
}
Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Malloc Query Pushpa <pushpa@nospam.invalid> - 2011-05-17 19:39 +0000
Re: Malloc Query blp@cs.stanford.edu (Ben Pfaff) - 2011-05-17 12:55 -0700
Re: Malloc Query "BartC" <bc@freeuk.com> - 2011-05-18 12:05 +0100
Re: Malloc Query Pushpa <pushpa@nospam.invalid> - 2011-05-18 17:11 +0000
Re: Malloc Query "BartC" <bc@freeuk.com> - 2011-05-18 22:42 +0100
Re: Malloc Query Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-05-18 21:10 -0400
Re: Malloc Query Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-18 19:34 +0100
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-18 17:10 -0400
Re: Malloc Query Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-19 00:26 +0100
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-18 21:25 -0400
Re: Malloc Query James Kuyper <jameskuyper@verizon.net> - 2011-05-18 21:38 -0400
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-19 14:11 -0400
Re: Malloc Query James Kuyper <jameskuyper@verizon.net> - 2011-05-19 22:55 -0400
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-20 12:14 -0400
Re: Malloc Query Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-19 03:22 +0100
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-19 14:20 -0400
Re: Malloc Query Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-19 23:51 +0100
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-19 20:01 -0400
Re: Malloc Query luser- -droog <mijoryx@yahoo.com> - 2011-05-22 02:49 -0700
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-22 10:46 -0400
Re: Malloc Query Shao Miller <sha0.miller@gmail.com> - 2011-05-22 12:37 -0500
Re: Malloc Query Shao Miller <sha0.miller@gmail.com> - 2011-05-22 13:02 -0500
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-22 14:12 -0400
Re: Malloc Query Shao Miller <sha0.miller@gmail.com> - 2011-05-23 03:06 -0500
Re: Malloc Query luser- -droog <mijoryx@yahoo.com> - 2011-05-23 00:42 -0700
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-23 11:10 -0400
Re: Malloc Query Keith Thompson <kst-u@mib.org> - 2011-05-23 09:06 -0700
Re: Malloc Query Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-22 23:18 +0100
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-22 19:18 -0400
Re: Malloc Query Ian Collins <ian-news@hotmail.com> - 2011-05-23 11:22 +1200
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-23 01:57 -0400
Re: Malloc Query Ian Collins <ian-news@hotmail.com> - 2011-05-23 19:24 +1200
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-23 14:20 -0400
Re: Malloc Query Ian Collins <ian-news@hotmail.com> - 2011-05-24 07:41 +1200
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-23 16:24 -0400
Re: Malloc Query Ian Collins <ian-news@hotmail.com> - 2011-05-24 09:20 +1200
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-23 18:05 -0400
Re: Malloc Query Ian Collins <ian-news@hotmail.com> - 2011-05-24 10:37 +1200
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-23 19:34 -0400
Re: Malloc Query "robertwessel2@yahoo.com" <robertwessel2@yahoo.com> - 2011-05-23 17:48 -0700
Re: Malloc Query Ian Collins <ian-news@hotmail.com> - 2011-05-24 12:56 +1200
Re: Malloc Query James Kuyper <jameskuyper@verizon.net> - 2011-05-24 07:19 -0400
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-24 11:32 -0400
Re: Malloc Query Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-23 01:04 +0100
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-23 02:36 -0400
Re: Malloc Query luser- -droog <mijoryx@yahoo.com> - 2011-05-23 00:39 -0700
Re: Malloc Query Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-23 14:44 +0100
Re: Malloc Query Seebs <usenet-nospam@seebs.net> - 2011-05-23 15:16 +0000
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-23 11:41 -0400
Re: Malloc Query David Thompson <dave.thompson2@verizon.net> - 2011-06-01 16:33 -0400
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-19 18:34 -0400
Re: Malloc Query Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-20 02:36 +0100
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-20 12:26 -0400
Re: Malloc Query Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-20 23:32 +0100
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-20 21:17 -0400
Re: Malloc Query Ian Collins <ian-news@hotmail.com> - 2011-05-21 14:30 +1200
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-21 11:13 -0400
Re: Malloc Query Ian Collins <ian-news@hotmail.com> - 2011-05-22 08:50 +1200
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-21 20:03 -0400
Re: Malloc Query Ian Collins <ian-news@hotmail.com> - 2011-05-22 13:23 +1200
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-22 10:01 -0400
Re: Malloc Query "io_x" <a@b.c.invalid> - 2011-05-26 08:12 +0200
Re: Malloc Query Ian Collins <ian-news@hotmail.com> - 2011-05-26 19:16 +1200
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-26 15:03 -0400
Re: Malloc Query Ian Collins <ian-news@hotmail.com> - 2011-05-27 09:16 +1200
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-26 17:55 -0400
Re: Malloc Query "io_x" <a@b.c.invalid> - 2011-05-27 05:47 +0200
Re: Malloc Query Uncle Steve <stevet810@gmail.com> - 2011-05-26 15:02 -0400
Re: Malloc Query "BartC" <bc@freeuk.com> - 2011-05-18 22:31 +0100
Re: Malloc Query Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-18 23:37 +0100
Re: Malloc Query "BartC" <bc@freeuk.com> - 2011-05-19 01:50 +0100
Re: Malloc Query Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-19 02:50 +0100
Re: Malloc Query "BartC" <bc@freeuk.com> - 2011-05-19 12:14 +0100
Re: Malloc Query Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-19 15:10 +0100
Re: Malloc Query "BartC" <bc@freeuk.com> - 2011-05-19 15:48 +0100
Re: Malloc Query cri@tiac.net (Richard Harter) - 2011-05-18 19:31 +0000
Re: Malloc Query Ike Naar <ike@iceland.freeshell.org> - 2011-05-18 21:43 +0000
Re: Malloc Query "BartC" <bc@freeuk.com> - 2011-05-18 22:58 +0100
Re: Malloc Query Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-05-17 14:01 -0600
Re: Malloc Query Columbus sailed the ocean China Blue <chine.bleu@yahoo.com> - 2011-05-17 13:21 -0700
Re: Malloc Query BGB <cr88192@hotmail.com> - 2011-05-17 14:08 -0700
Re: Malloc Query Michael Press <rubrum@pacbell.net> - 2011-05-17 19:49 -0700
Re: Malloc Query Lauri Alanko <la@iki.fi> - 2011-05-18 00:50 +0000
Re: Malloc Query Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-05-17 21:21 -0400
Re: Malloc Query "io_x" <a@b.c.invalid> - 2011-05-18 19:31 +0200
Re: Malloc Query Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-05-18 21:36 +0000
Re: Malloc Query Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-05-18 21:26 -0400
Re: Malloc Query Tim Rentsch <txr@alumni.caltech.edu> - 2011-05-19 02:07 -0700
Re: Malloc Query Ian Collins <ian-news@hotmail.com> - 2011-05-19 21:13 +1200
Re: Malloc Query Nobody <nobody@nowhere.com> - 2011-05-18 07:08 +0100
Re: Malloc Query David Resnick <lndresnick@gmail.com> - 2011-05-19 07:51 -0700
Re: Malloc Query Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-05-19 09:12 -0600
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