by joh.. » Thu, 16 Dec 1999 04:00:00
What is the optimum buffer size to malloc.
Is it best to malloc in 1K size blocks, the system page size or
something else?
Specifics
---------
OS : Solaris 2.5.1
Page Size: 8192 bytes
Any input would be appreciated!
John
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Before you buy.
by Kenneth C Stah » Thu, 16 Dec 1999 04:00:00
> I have a record size of 29 bytes and I want
> to malloc a buffer to hold an unknown number
> of records. When that buffer gets full, realloc
> another block on.
> What is the optimum buffer size to malloc.
> Is it best to malloc in 1K size blocks, the system page size or
> something else?
> Specifics
> ---------
> OS : Solaris 2.5.1
> Page Size: 8192 bytes
> Any input would be appreciated!
> John
> Sent via Deja.com http://www.deja.com/
> Before you buy.
by Keith Thompso » Thu, 16 Dec 1999 04:00:00
BUFSIZ is in stdio.h, not stdlib.h.Quote:> I'd suggest using BUFSIZ from stdlib.h. On most systems it is either 512 or
> 1024, but if you use the header file definition you will be more portable
> than if you specify a literal value yourself.
Note that this is the size of an I/O buffer. It's not clear (to me)
that this will be the most efficient size for malloc, though it's
likely not to be terribly inefficient.
Suggestion: Try several different values and do some profiling.
--
San Diego Supercomputer Center <*> <http://www.sdsc.edu/~kst>
"Oh my gosh! You are SO ahead of your time!" -- anon.
1. does realloc(NULL,size) work like malloc(size) on SunOS 4.1.3 or AIX 2
%% Regarding [Q] does realloc(NULL,size) work like malloc(size) on SunOS
cz> has anyone noticed that realloc(NULL,size) does not work like
cz> malloc(size) on SunOS 4.1.3 or AIX 2? the man page for realloc()
cz> claims that realloc() should act like malloc when it gets a NULL
cz> ptr.
Whose man page? Not SunOS's anyway, not on my SunOS 4.1.3_U1 :)
According to ANSI C, conforming implementations of the C runtime library
should treat realloc(NULL,size) the same as malloc(size).
However, certainly no one's ever accused SunOS 4.1.x of having a C
runtime library that comes close to conforming to ANSI C (despite the
fact that it's been a standard for 7 years). AIX 2 sounds old enough
that it also is suspect.
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