Hi All,
I have just discovered that for extended CSA, page tables exist for
all storage within the CSA, even for whole segments (mega-byte
chunks) that are in unallocated storage.
In other words, for CSA storage, even when every page within a
segment's page table is flagged as being "invalid"
(x'0000000000000400'), (a) the page table continues to exist, and (b)
the segment table entry pointing to that page table is *NOT* flagged
as being invalid!
I have two questions:
(1) Why does IBM do this?
(2) Has it always been this way? (I think not, but I'm not sure.)
Why do I care? Well, I have a storage search routine that traps the
program checks that occur when unallocated storage is reached, and
examines the PIC codes to figure out how far ahead to jump to step
over the hole. This logic works great for private storage, but for
CSA, I wind up getting 71-THOUSAND page faults instead of only a few
hundred segment faults. Consequently, a scan that should take only a
few seconds winds up taking between a quarter and a half hour.
(I know what I need to do to "fix" this. I'm just curious about what
good reason IBM might or might not have for doing this.)
Thanks,
Dave Cole REPLY TO: [EMAIL PROTECTED]
Cole Software WEB PAGE: http://www.colesoft.com
736 Fox Hollow Road VOICE: 540-456-8536
Afton, VA 22920 FAX: 540-456-6658
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