Cache Efficiency & Page Sizes

[noodles1]

Does anyone know if the previously known issue about Page Sizes that are not derived from a power of 2 (ie. 1536, 2560, 3072, 3584) being wasteful of Cache is still relevant?

If no longer an issue, in what version was the situation amended?

 

[Linda84]

It is still a waste of cache memory to use non-power-of-two page sizes. In Pervasive.SQL servers, the MKDE cache is a buddy system cache, always has been, and it divides up memory blocks by dividing them in two. A 4096 buffer can be split in half and made available to hold two 2048 pages, and one of those can be split in half to hold 1024 byte pages. Page sizes of 2560, 3072, and 3584 must use 4096 byte buffers from cache and they always waste memory. Likewise, 1536 byte pages must use a 2048 byte buffer.



Linda
Pervasive Software Support