On Mon, 2010-08-23 at 16:56 -0600, Paul Gilmartin wrote: <snip> > If the table is kept in a binary tree with a 4-byte key and two 4-byte > pointers (possibly relative to table base), the size for a million entries > is 12 MB, far smaller than DASD Bill's bitmap. And initializing > a 537 MB table is a brutal hit on the cache. When the table contains > a million entries, there is only a 0.25 probability that any 1024-bit > cache line will contain a 1-bit.
Thanks to the way that z/OS works, there is no need to initialize the table. Do the STORAGE OBTAIN and use BNDRY=PAGE. When a never before used page is first referenced, a free frame is assigned and initialized to all x'00' for security/integrity reasons. This means that the entire 537Meg is implicitly initialized to x'00', which is what is desired. Unused pages are never really allocated. But the page table entries are initialized. And consume real memory (in LSQA?). But I agree that this huge table will likely cause paging problems. <snip> > -- gil
