02-21-2005
i think that shared mem is the faster of the two. this question really belongs in the c programming category doesn't it?
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I am running HP-UX B.11.11.
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Between mmap and shared memory which is the best method of sharing data between multiple applications, interms of speed? (1 Reply)
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hi,
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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.
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Hello,
I wonder if I can write my userdefined data structures(ex: a list) to a shared memory segment?
I know, the shm functions get (void*) parameter so I should be able to read and write a list into the shared memory.
may someone inform and clarify me about that, please? (1 Reply)
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Hey, Im using a shared memory segment to share a WINDOW structure among 2 processes. Basically I'm building a multi-player snake game in which multiple prrocesses access the window.
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I'll try to keep this short, but basically I need to figure out a way to load data in shared memory (this file will be called load.c) I will later access the data with a print.c program.
The "data" is in the form of a student database that looks like this
John Blakeman
111223333
560... (7 Replies)
Discussion started by: Mercfh
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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.
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MEM(4) Linux Programmer's Manual MEM(4)
NAME
mem, kmem, port - system memory, kernel memory and system ports
DESCRIPTION
mem is a character device file that is an image of the main memory of the computer. It may be used, for example, to examine (and even
patch) the system.
Byte addresses in mem are interpreted as physical memory addresses. References to nonexistent locations cause errors to be returned.
Examining and patching is likely to lead to unexpected results when read-only or write-only bits are present.
It is typically created by:
mknod -m 660 /dev/mem c 1 1
chown root:kmem /dev/mem
The file kmem is the same as mem, except that the kernel virtual memory rather than physical memory is accessed.
It is typically created by:
mknod -m 640 /dev/kmem c 1 2
chown root:kmem /dev/kmem
port is similar to mem, but the I/O ports are accessed.
It is typically created by:
mknod -m 660 /dev/port c 1 4
chown root:mem /dev/port
FILES
/dev/mem
/dev/kmem
/dev/port
SEE ALSO
chown(1), mknod(1), ioperm(2)
COLOPHON
This page is part of release 3.25 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
Linux 1992-11-21 MEM(4)