/*
* BufferShmemSize
*
* compute the size of shared memory for the buffer pool including
* data pages, buffer descriptors, hash tables, etc.
*/
Size
BufferShmemSize(void)
{
Size size = 0;
/* size of buffer descriptors */
size = add_size(size, mul_size(NBuffers, sizeof(BufferDescPadded)));
/* to allow aligning buffer descriptors */
size = add_size(size, PG_CACHE_LINE_SIZE);
/* size of data pages */
size = add_size(size, mul_size(NBuffers, BLCKSZ));
/* size of stuff controlled by freelist.c */
size = add_size(size, StrategyShmemSize());
/*
* It would be nice to include the I/O locks in the BufferDesc, but that
* would increase the size of a BufferDesc to more than one cache line,
* and benchmarking has shown that keeping every BufferDesc aligned on a
* cache line boundary is important for performance. So, instead, the
* array of I/O locks is allocated in a separate tranche. Because those
* locks are not highly contentended, we lay out the array with minimal
* padding.
*/
size = add_size(size, mul_size(NBuffers, sizeof(LWLockMinimallyPadded)));
/* to allow aligning the above */
size = add_size(size, PG_CACHE_LINE_SIZE);
/* size of checkpoint sort array in bufmgr.c */
size = add_size(size, mul_size(NBuffers, sizeof(CkptSortItem)));
return size;
}
/*
* BufferShmemSize
*
* compute the size of shared memory for the buffer pool including
* data pages, buffer descriptors, hash tables, etc.
*/
Size
BufferShmemSize(void)
{
Size size = 0;
/* size of buffer descriptors */
size = add_size(size, mul_size(NBuffers, sizeof(BufferDesc)));
/* size of data pages */
size = add_size(size, mul_size(NBuffers, BLCKSZ));
/* size of stuff controlled by freelist.c */
size = add_size(size, StrategyShmemSize());
return size;
}
/*
* BufferShmemSize
*
* compute the size of shared memory for the buffer pool including
* data pages, buffer descriptors, hash tables, etc.
*/
int
BufferShmemSize(void)
{
int size = 0;
/* size of buffer descriptors */
size += MAXALIGN(NBuffers * sizeof(BufferDesc));
/* size of data pages */
size += NBuffers * MAXALIGN(BLCKSZ);
/* size of stuff controlled by freelist.c */
size += StrategyShmemSize();
return size;
}
