In <[EMAIL PROTECTED]>, on 08/27/2005
at 06:50 AM, Charles Mills <[EMAIL PROTECTED]> said:
>Does MVS (DFSMS, whatever) still do that? What we used to call
>"double buffering"?
Not exactly. The old SAM-E is included in DFSMSdfp, and the SAM
scheduling code tries to build a full channel program, subject to some
arbitrary cutoff points. If there is another channel program built,
then appendage logic will initiate it. If you have a large number of
buffers then the cutoff will not allow half of them to be in a single
channel program.
Actually, OS/360 et al have never used double buffering. They've
always allowed you to have more than 2 buffers. It's just that the
SAM-E code makes more effective use of the extra buffers than the old
OPTCD=C code did.
--
Shmuel (Seymour J.) Metz, SysProg and JOAT
ISO position; see <http://patriot.net/~shmuel/resume/brief.html>
We don't care. We don't have to care, we're Congress.
(S877: The Shut up and Eat Your spam act of 2003)
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