pSOSystem System Calls - Read

pNA+ System Calls pna_allocb
pna_allocb Allocates a message block.
#include
mblk_t *pna_allocb(size, pri)
int size;
int pri;
Description
Arguments
Return Value
pna_allocb allocates a message block with a data buffer of a specified size.
The pNA+ memory manager searches the buffer list for the size that best fits the
requested size. If a buffer of that size is not available, the call returns NULL.
pna_allocb uses the following algorithm to find the best fit:
1. The pNA+ memory manager first searches for an exact match.
2. If a match is not available, the pNA+ memory manager searches for the smallest
size able to contain the requested size.
3. If none is available, the maximum size configured in the pNA+ memory manager
is used.
The following example illustrates this algorithm:
Let buffers of sizes 0, 128, 1024, and 4096 bytes be configured in pNA+. If a buffer
of size 1024 is requested, the pNA+ memory manager allocates a buffer from the
1024-byte buffer list. A request for a 2048-byte buffer results in the pNA+ memory
manager allocating a buffer from the 4096-byte buffer list, and a request for a size
8192 buffer results in the allocation of a 4096-byte buffer.
size Specifies the size of the data buffer.
pri Unused by the pNA+ memory manager.
This system call returns a pointer to the message block if successful; otherwise, it
returns a null pointer.
pSOSystem System Calls 4-39
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