Shared Memory Post: 302282811

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1. Programming

Shared memory

Dear Reader, Is is necessary to attach / dettach the shared memory segments for write operations , if more than one program is accessing same shared memory segments.. I have used semaphore mutex and still I'm getting segmentation fault when I write to the segment when other program is already...

2. UNIX for Advanced & Expert Users

Shared memory shortage but lots of unused memory

I am running HP-UX B.11.11. I'm increasing a parameter for a database engine so that it uses more memory to buffer the disk drive (to speed up performance). I have over 5GB of memory not being used. But when I try to start the DB with the increased buffer parameter I get told. "Not...

3. Linux

all about shared memory

Hi all :confused: , I am new to unix.I have been asked to implement shared memory in user's mode.What does this mean?What is the difference it makes in kernel mode and in users mode?What are the advantages of this impemenation(user's mode)? And also i would like to know why exactly shared...

4. Programming

implement shared memory

hi all I have been asked to implement shared memory in user mode?But :rolleyes: im not understanding how to do this.And what does it mean in user mode?Is it that we need to simulate what kernal does...like attaching ,detaching memory..etc...? And would also like to know why shared memory is...

5. Programming

help with shared memory

what i want to do is have an int that can been written into by 2 processes but my code doesn't seem to work. #include <sys/types.h> #include <sys/ipc.h> #include <sys/sem.h> #include <sys/shm.h> #include<stdio.h> #define KEY1 (1492) int main() { int shmid; volatile int * addr;...

6. Programming

memory sharing - not shared memory -

hi, this is the problem: i want to swap a linked list between 4 processes (unrelated), is there any way i can do that just by sending a pointer to a structure? //example typedef struct node { int x; char c; struct node *next; } node; or i should send the items ( x,c ) by...

7. Programming

Shared memory in shared library

I need to create a shared library to access an in memory DB. The DB is not huge, but big enough to make it cumbersome to carry around in every single process using the shared library. Luckily, it is pretty static information, so I don't need to worry much about synchronizing the data between...

8. Programming

Shared memory for shared library

I am writing a shared library in Linux (but compatible with other UNIXes) and I want to allow multiple instances to share a piece of memory -- 1 byte is enough. What's the "best" way to do this? I want to optimize for speed and portability. Obviously, I'll have to worry about mutual exclusion.

9. AIX

shared memory

1.How to know wich process is using the shared memory? 2.How to flush (release) the process from the shared memory?

10. Programming

Shared library with acces to shared memory.

Hello. I am new to this forum and I would like to ask for advice about low level POSIX programming. I have to implement a POSIX compliant C shared library. A file will have some variables and the shared library will have some functions which need those variables. There is one special...

LEARN ABOUT MOJAVE

ipcrm

ipcrm(1)						    BSD General Commands Manual 						  ipcrm(1)

NAME

     ipcrm -- remove the specified message queues, semaphore sets, and shared memory segments

SYNOPSIS

     ipcrm [-M shmkey] [-m shmid] [-Q msgkey] [-q msqid] [-S semkey] [-s semid] ...

DESCRIPTION

     Ipcrm removes the specified message queues, semaphores and shared memory segments.  These System V IPC objects can be specified by their cre-
     ation id or any associated key.

     The following options are used to specify which IPC objects will be removed.  Any number and combination of these options can be used:

     -M shmkey
	     Mark the shared memory segment associated with key shmkey for removal.  This marked segment will be destroyed after the last detach.

     -m shmid
	     Mark the shared memory segment associated with id shmid for removal.  This marked segment will be destroyed after the last detach.

     -Q msgkey
	     Remove the message queue associated with key msgkey from the system.

     -q msqid
	     Remove the message queue associated with the id msqid from the system.

     -S semkey
	     Remove the semaphore set associated with key semkey from the system.

     -s semid
	     Removes the semaphore set associated with id semid from the system.

     The identifiers and keys associated with these System V IPC objects can be determined by using ipcs(1)

SEE ALSO

     ipcs(1)

BSD
								  August 8, 1994							       BSD