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-   -   Problem in allocating shared memory size more then 672 (

shashwat.gupta 05-08-2006 12:31 PM

Problem in allocating shared memory size more then 672
Hi there,

I am using Redhat Enterprise Linux 3. I am using it on 512 MB RAM . For some application I want shared memory up to 2.5 GB. I was just trying to get shared memory through simple program that uses shmget system call. for memory allocation. I changed the entry of shmmax with command echo "1073741824" >/proc/sys/kernel/shmmax

Then try to execute a program which allocate shared memory
sharedmemory.c as follows --
#include <sys/types.h>
#include <sys/ipc.h>

#include <sys/shm.h>
#include <errno.h>
#include <stdio.h>

#include <sys/time.h>
#include <sys/resource.h>
#include <unistd.h>

int main(){

key_t key = 1311;

int m_shmid = shmget(key,1048576*1024,IPC_CREAT|0666);
/*trying to allocate memory size of 1GB */
printf("m_shmid value is %d", m_shmid);

/*some header file are extra pleasse do not mind*/

The shmid value comes out to be -1 surprisingly method works perfectly when I try to allocate the memory up to 688128*1024 bytes (That is 672 MB) I donot reason please tell me any thing I need to do make it work

I am executing all commands on root permission

crabboy 05-08-2006 01:15 PM

Please do not post the same thread in more than one forum. Picking the most relevant forum and posting it once there makes it easier for other members to help you and keeps the discussion all in one place.

Continue discussion here:

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