Sharing memory between two processes

Question

I want to share memory between two processes. One way I know is to mmap a shared file. However, I don't want to use a shared file, I want an anonymous mapping in the memory. How can I do that.

MetallicPriest · Accepted Answer · 2012-07-20 16:25:36Z

5

shm_open is your friend. You can unmap the shared region by using shm_unlink.

answered Jul 20, 2012 at 16:25

MetallicPriest

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tbert · Accepted Answer · 2012-07-20 16:21:58Z

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Shared memory is what you want: http://en.wikipedia.org/wiki/Shared_memory

Since you're on linux, here you go: http://www.kernel.org/doc/man-pages/online/pages/man7/shm_overview.7.html

answered Jul 20, 2012 at 16:21

tbert

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MarkR · Accepted Answer · 2012-07-20 16:24:22Z

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You can put your mmap'd file in the directory /dev/shm, which is mounted in most Linux systems as a tmpfs (that is, a memory-based filesystem).

Or your can mount your own tmpfs somewhere else in the directory tree (if you want other options).

answered Jul 20, 2012 at 16:24

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Ed Heal · Accepted Answer · 2012-07-20 16:26:39Z

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shm_get is a good starting point, but you also need to read up about semaphores for mutual exclusion so that memory does not get corrupted.

answered Jul 20, 2012 at 16:26

Ed Heal

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user82238 · Accepted Answer · 2012-07-20 16:43:11Z

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Remember that on a NUMA system, if cores are on separate nodes they will access the memory at different speeds unless you pick a NUMA node which is equidistant from the cores.

answered Jul 20, 2012 at 16:43

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