Does it make sense to reduce the total shared memory
We have several dozen Redhat 5, 6 and 7 servers that are running Oracle databases. On some databases we are using automatic memory management, which uses shared memory. On other databases we are use manual memory management, which does not use shared memory.
When I see that a server is swapping and not using that much shared memory, does it make sense to shrink the amount of shared memory allocated to reduce the swap usage? I have read that setting /dev/shm does not allocate memory. But I wonder if it is still preventing non shared memory from staying in physical 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... (1 Reply)
I am using the ZLIB_VERSION "1.2.3" . The memory requirement for Zlib/GZIP compression is stated as
/* The memory requirements for deflate are (in bytes):
(1 << (windowBits+2)) + (1 << (memLevel+9))
that is: 128K for windowBits=15 + 128K for memLevel = 8 (default values)
... (0 Replies)
08-18-2008 11:00 AM
Cluster computing has played a pivotal role in the way research is conducted in educational environments. Because the amount of available money and hardware varies between university researchers, often it's necessary to find a clustering solution that can work well on a small... (0 Replies)
I've been referring bash info for processes and came across a structure for a process which is defined like
typedef struct process
{
struct process *next;
char ** argv
.
.
.
}process;
What I don't understand is that in the program there's a for loop which goes like this
job... (2 Replies)
Hi,
Im working on Solaris 9 on SPARC-32 bit running on an Ultra-80, and I have to find out the following:-
1. Total Physical Memory in the system(total RAM).
2. Available Physical Memory(i.e. RAM Usage)
3. Total (Logical) Memory in the system
4. Available (Logical) Memory.
I know... (4 Replies)
I'm running the following rsync command to sync a directory between the 2 servers:
rsync -az --delete --stats /some_dir/ server_name:/some_dir
I'm getting the following output:
Number of files: 655174
Number of files transferred: 14221
Total file size: 1138531979331 bytes
Total... (0 Replies)
Can someone explain the correlation between how sar names the disk drives and how the rest of the OS names the disk drives?
sar lists my disk drives as sd0, sd1, sd2, etc.....
while format lists my disk drives as c1t0d0, c1t1d0, c1t2d0,etc...
And also why sar shows 8 disks but format... (2 Replies)
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)
I stumbled upon this thread and one aspect of it got me thinking. As i am building a small Linux network right now for a friend i would like to hear your opinion on this.
I'd like to respectfully disagree. I think the Linux habit of disabling root login per default is wrong (not entirely... (6 Replies)
I am using xlC (Version: 11.01.0000.0011).
While build i am using "-g" to have debug information in build.
there are many object files (>500) due to which resultant shared file (.so) will have huge size.
I can't reduce optimization level.
Is there any way or flag is present by using which i... (2 Replies)
Discussion started by: Abhi04
2 Replies
LEARN ABOUT ULTRIX
shmget
shmget(2) System Calls Manual shmget(2)Name
shmget - get shared memory segment
Syntax
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
int shmget (key, size, shmflg)
key_t key;
int size, shmflg;
Description
The system call returns the shared memory identifier associated with key.
A shared memory identifier and associated data structure and shared memory segment of size size bytes are created for key, if one of the
following is true:
The key is equal to IPC_PRIVATE. For further information, see
The key does not already have a shared memory identifier associated with it, and (shmflg & IPC_CREAT ) is true.
Upon creation, the data structure associated with the new shared memory identifier is initialized as follows:
The and are set equal to the effective user ID and effective group ID of the calling process.
The low-order nine bits of are set equal to the low-order nine bits of shmflg. The is set equal to the value of size.
The and are set equal to zero (0). The shm_ctime is set equal to the current time.
Return Values
Upon successful completion, a non-negative integer, namely, a shared memory identifier is returned. Otherwise, a value of -1 is returned
and errno is set to indicated the error.
Diagnostics
The system call fails if any of the following is true:
[EINVAL] The size is less than the system-imposed minimum or greater than the system-imposed maximum.
[EACCES] A shared memory identifier exists for key, but operations permission, as specified by the low-order nine bits of shmflg,
would not be granted. For further information, see
[EINVAL] A shared memory identifier exists for key, but the size of the segment associated with it is less than size and size is not
equal to zero.
[ENOENT] A shared memory identifier does not exist for key, and (shmflg & IPC_CREAT ) is false.
[ENOSPC] A shared memory identifier is to be created, but the system-imposed limit on the maximum number of allowed shared memory
identifiers would be exceeded.
[ENOMEM] A shared memory identifier and the associated shared memory segment are to be created, but the amount of available physical
memory is not sufficient to fill the request.
[EEXIST] A shared memory identifier exists for key, but ((shmflg & IPC_CREAT ) and (shmflg & IPC_EXCL )) is true.
See Alsoshmctl(2), shmop(2), ftok(3)shmget(2)