dshm_minmapsize(DSHM)

dshm_minmapsize -- compute DSHM minimum map size

Synopsis

   #include <dshm.h>
   
   size_t	dshm_minmapsize (size_t buffer_size, unsigned long max_mappings);

Description

dshm_minmapsize returns the minimum map size required to support a given number of concurrent mappings of a given buffer size on the current machine.

Return values

dshm_minmapsize returns the minimum map size, in bytes

If dshm_minmapsize returns size_t -1, an error occurred. errno is set to identify the error.

Errors

In the following conditions, dshm_minmapsize fails and sets errno to:

EINVAL: buffer_size is not a power of 2.
EINVAL: buffer_size is greater than DSHM_MAX_BUFFER_SIZE.
ENOSYS: DSHM is not supported.
EOVERFLOW: The required map size cannot fit in a size_t

References

dshm_alignment(DSHM), dshm_attach(DSHM), dshm_bufindex(DSHM), dshm_control(DSHM), dshm_detach(DSHM), dshm_get(DSHM), dshm_map(DSHM), dshm_reattach(DSHM), dshm_unmap(DSHM), dshm_updatetlb(DSHM)