02-28-2006
all about shared memory
Hi all
,
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 memory called the fastest IPC mechanism?
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shmem(5) File Formats Manual shmem(5)
NAME
shmem - enable or disable System V shared memory
DESCRIPTION
The tunable is obsolete. The System V IPC shared memory subsystem is always enabled.
Shared memory is an efficient InterProcess Communications (IPC) mechanism. One process creates a shared memory segment and attaches it to
its address space. Any processes looking to communicate with this process through the shared memory segment, then attach the shared memory
segment to their corresponding address spaces as well. Once attached, a process can read from or write to the segment depending on the
permissions specified while attaching it.
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.
SEE ALSO
shmmax(5), shmmni(5), shmseg(5).
Tunable Kernel Parameters shmem(5)