[Qt-interest] QSharedMemory limits on Mac OS X

[Brad Howes]

On Apr 14, 2010, at 8:34 AM, Frank Mertens wrote:

> Have you tried mmap() directly? It is not affected by the kern.sysv.* limits.
> SysV IPC is basicly there for backwards compatibility, nobody should use it anymore.


Huh? The SysV IPC stuff is legacy (calls like sem* and shm*), but there is a POSIX standard for IPC that is not (sem_* and shm_*).

IIRC, the big difference between POSIX shared memory and memory mapping (mmap) is that when multiple processes use the same mmap file, page faults are more likely, whereas in POSix shared memory, the shared address is the same in all processes. This may no longer be true or it may only pertain to some system I worked on in the past (perhaps AIX or Solaris).

Brad

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Brad Howes
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