03-16-2010
Shared memory is physical memory that is used by two or more different processes at the same time.
Ex: shared libraries. This is code that gets loaded into memory, and all processes running on the system see it an use it at the same time.
9 More Discussions You Might Find Interesting
1. UNIX for Advanced & Expert Users
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... (1 Reply)
Discussion started by: cjcamaro
1 Replies
2. Programming
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... (9 Replies)
Discussion started by: elzalem
9 Replies
3. Programming
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... (12 Replies)
Discussion started by: DreamWarrior
12 Replies
4. Programming
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. (0 Replies)
Discussion started by: otheus
0 Replies
5. UNIX for Advanced & Expert Users
Hi,
Using ipcs we can see shared memory, etc.. details. How can I add/remove shared memory(command name)?
Thanks,
Naga:cool: (2 Replies)
Discussion started by: Nagapandi
2 Replies
6. Red Hat
Dear Friends ,
I am confused about shared memory in Linux . plz look @ the below output :
$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 126G 61G 59G 52% /
tmpfs 1.7G 0 1.7G 0% /dev/shm
Here , I see that every time... (1 Reply)
Discussion started by: shipon_97
1 Replies
7. Red Hat
unable to remove shared memory using ipcrm -m in linux
$ ipcs -m
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x00000000 32768 root 644 80 2
0x00000000 65537 root ... (4 Replies)
Discussion started by: LinuxLearner
4 Replies
8. Programming
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... (5 Replies)
Discussion started by: iamjag
5 Replies
9. Programming
So I am pretty new to the linux environment, and I am trying to create a shell that uses multiple pipes, and I read online that piping using shared memory space is more efficient than using regular piping. However, I have zero clue how to use shared memory space with pipes. Has anyone done this... (1 Reply)
Discussion started by: Greg_MC
1 Replies
LEARN ABOUT HPUX
unlockable_mem
unlockable_mem(5) OBSOLETE unlockable_mem(5)
NAME
unlockable_mem - OBSOLETE kernel tunable parameter
DESCRIPTION
The tunable is obsolete and has been removed.
Memory locking allows the privileged user to specify which pages need to remain in memory, and unaffected by the swap process. This fea-
ture allows you to ensure that memory access times are unaffected by delays introduced by memory paging and swapping. For example, locking
is a tool provided to privileged users on a system that is short on physical memory. Instead of having these privileged processes swap
like the rest of the processes, they can lock portions of their address space. Once the pages are locked in for the privileged processes,
they will no longer have to worry about memory contention. The unprivileged processes however, will have to compete for memory.
provides you with a limiting factor on this privileged behavior, by setting the amount of memory which cannot be locked by user processes.
WARNINGS
Installation of optional kernel software, from HP or other vendors, may cause changes to tunable parameter values. After installation,
some tunable parameters may no longer be at the default or recommended values. For information about the effects of installation on tun-
able values, consult the documentation for the kernel software being installed. For information about optional kernel software that was
factory installed on your system, see at
AUTHOR
was developed by HP.
Tunable Kernel Parameters unlockable_mem(5)