RE: Porting C Linux to ILE C: Performance problem

Realloc is always a poor performer as it needs to allocate a new block large
enough to fit the request, then copy the memory from the old location to the
new one and then return.

As a general rule, I try and limit the malloc's and free's that a program
uses as much as possible.  They tend to be expensive and make performance
very non-linear.  This is both AS/400 and Windows.  Havent done much
Linux/Unix work so I don't know about that.

Bob

> -----Original Message-----
> From: c400-l-bounces@xxxxxxxxxxxx [mailto:c400-l-bounces@xxxxxxxxxxxx] On
> Behalf Of Zvi Kave
> Sent: Wednesday, June 30, 2004 9:29 AM
> To: c400-l@xxxxxxxxxxxx
> Subject: [C400-L] Porting C Linux to ILE C: Performance problem
> 
> Dear collegues,
> 
> 1. I ported succesfully(?) C coded software from Linux
> 
>    to ILE C.
> 2. The sample program I use, takes in Linux 1 second.
>    The same program run takes on the AS/400 ...
>    7 minutes!?
> 3. When debugging the program on the AS/400, I found
>    that the slow response is in the memory allocation
>    routines, namely, calloc, malloc, realloc and
>    free().
>    CPU usage is about 10%.
> 4. Those memory management routines are managed by
>    linked list which is allocated in the beginning of
>    program and free()d before end.
> 
>  Is there any reason for that performance problem?
> 
>   Please help.
> 
>   Regards,
> 
>    Zvi
> 
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