10 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
I am using ubuntu. I have written a program to calculate prime factors. it works perfectly fine till entered number is less than 9989 (or so ) but when one enters a number higher than that, for example 15000, it does not work. Can anyone guide me whats the problem ? although new codes are welcome,... (2 Replies)
Discussion started by: Abhishek_kumar
2 Replies
2. Red Hat
Hi, I have a Linux distribution ( Oralce Enterprise Linux 5.3 i.e. Redhat ) that I have installed. It works fine when I used 2*512Mb dimms or replace them with a single 1Gb dimm. However when I try to go above 1 Gb the bootup and general performance deteriorates badly. The BIOS picks up the memory... (3 Replies)
Discussion started by: jimthompson
3 Replies
3. HP-UX
Hi,
This is my 1st post here. I am facing a rather weired problem. I have a C++ binary running on HP-UX. The output of top as well as glance shows periodic increase in memory. But when i use gdb to detect it, i dont get the desired output...gdb says...no leaks found. Just to mention that I have... (2 Replies)
Discussion started by: kshk123
2 Replies
4. Programming
hi all
Can any one plz explain me about memory leak problem
Thankx (5 Replies)
Discussion started by: sonali
5 Replies
5. Programming
I have a program that will fetch some particular lines and store it in a buffer for further operations.The code which is given below works but with some errors.I couldn't trace out the error.Can anybody help on this plz??
#include <stdio.h>
#include <stdlib.h>
#include<string.h>
#define... (1 Reply)
Discussion started by: vigneshinbox
1 Replies
6. Shell Programming and Scripting
how the data from disk is loaded into memory and then it supplied to tcp/ip packet.
how i can trace the no of pages loaded in memory by that process and rate of context switch for that process. (1 Reply)
Discussion started by: amar20
1 Replies
7. Solaris
i am building open source software on a solaris 8 machine
for couple of days i am getting error messages like
out of memory
or
no more processes and then build is failing
i tried with rebooting the machine but then after couple of days same problem is arising again.
can any one... (1 Reply)
Discussion started by: mobydick
1 Replies
8. Programming
Hi, I try to marshal a unsigned int and a char * into a buffer, and then unmarshal them later to get them out. I need to put the char * in the front and unsigned int at the end of the buffer. However, my system always give me "BUS ERROR". I am using Sun Sparcs Sloris 2.10.
My code to marshal... (6 Replies)
Discussion started by: nj302
6 Replies
9. Filesystems, Disks and Memory
Hi ,
One of java programs in our machine allocates 256M of heap memory and max of 512 memory(Tomcat to be specific).
Our ulimit per process is 32M.How can a process allocates such a big amount of memory
ps v output is
PGIN SIZE RSS LIM TSIZ TRS %CPU %MEM COMMAND
24 220776 220892... (0 Replies)
Discussion started by: ganti
0 Replies
10. Programming
Hi:
I have a server with a very little memory leak (29 bytes) as reported by Purify.
Itīs a pooled server, so each process lives forever accepting conections.But top or ps commands show that used memory it is always increasing much more than 29 bytes (30K mor or less) in each conection.
How... (0 Replies)
Discussion started by: Pablo J. Royo
0 Replies
libtalloc_pools(3) talloc libtalloc_pools(3)
NAME
libtalloc_pools - Chapter 5: Memory pools
Memory pools
Allocation of a new memory is an expensive operation and large programs can contain thousands of calls of malloc() for a single
computation, where every call allocates only a very small amount of the memory. This can result in an undesirable slowdown of the
application. We can avoid this slowdown by decreasing the number of malloc() calls by using a memory pool.
A memory pool is a preallocated memory space with a fixed size. If we need to allocate new data we will take the desired amount of the
memory from the pool instead of requesting a new memory from the system. This is done by creating a pointer that points inside the
preallocated memory. Such a pool must not be reallocated as it would change its location - pointers that were pointing inside the pool
would become invalid. Therefore, a memory pool requires a very good estimate of the required memory space.
The talloc library contains its own implementation of a memory pool. It is highly transparent for the programmer. The only thing that needs
to be done is an initialization of a new pool context using talloc_pool() - which can be used in the same way as any other context.
Refactoring of existing code (that uses talloc) to take the advantage of a memory pool is quite simple due to the following properties of
the pool context:
o if we are allocating data on a pool context, it takes the desired amount of memory from the pool,
o if the context is a descendant of the pool context, it takes the space from the pool as well,
o if the pool does not have sufficient portion of memory left, it will create a new non-pool context, leaving the pool intact
/* allocate 1KiB in a pool */
TALLOC_CTX *pool_ctx = talloc_pool(NULL, 1024);
/* Take 512B from the pool, 512B is left there */
void *ptr = talloc_size(pool_ctx, 512);
/* 1024B > 512B, this will create new talloc chunk outside
the pool */
void *ptr2 = talloc_size(ptr, 1024);
/* The pool still contains 512 free bytes
* this will take 200B from them. */
void *ptr3 = talloc_size(ptr, 200);
/* This will destroy context 'ptr3' but the memory
* is not freed, the available space in the pool
* will increase to 512B. */
talloc_free(ptr3);
/* This will free memory taken by 'pool_ctx'
* and 'ptr2' as well. */
talloc_free(pool_ctx);
The above given is very convenient, but there is one big issue to be kept in mind. If the parent of a talloc pool child is changed to a
parent that is outside of this pool, the whole pool memory will not be freed until the child is freed. For this reason we must be very
careful when stealing a descendant of a pool context.
TALLOC_CTX *mem_ctx = talloc_new(NULL);
TALLOC_CTX *pool_ctx = talloc_pool(NULL, 1024);
struct foo *foo = talloc(pool_ctx, struct foo);
/* mem_ctx is not in the pool */
talloc_steal(mem_ctx, foo);
/* pool_ctx is marked as freed but the memory is not
deallocated, accessing the pool_ctx again will cause
an error */
talloc_free(pool_ctx);
/* This deallocates the pool_ctx. */
talloc_free(mem_ctx);
It may often be better to copy the memory we want instead of stealing it to avoid this problem. If we do not need to retain the context
name (to keep the type information), we can use talloc_memdup() to do this.
Copying the memory out of the pool may, however, discard all the performance boost given by the pool, depending on the size of the copied
memory. Therefore, the code should be well profiled before taking this path. In general, the golden rule is: if we need to steal from the
pool context, we should not use a pool context.
Version 2.0 Tue Jun 17 2014 libtalloc_pools(3)