Re: Re: NUMCPU >1 = IEE331A EXCESSIVE DISABLED SPIN LOOP DETECTED

On May 20, 2010, at 10:42 AM, yvette hirth wrote:

>> "DIE" ??
>
> Disabled Interrupt Exit.  runs disabled (for interrupts).

In this context it is the DIE within Basic IOS, and which replaced  
the PCI Appendage in MVT, et. al., and which allows synchronous  
(i.e., real-time) operations of I/O devices and the software,  
including device drivers and dependent applications.

It doesn't take that long for the header on a CONTROL/RLD record to  
be read, but the responding software, IEWFETCH, must be absolutely  
certain that the data is in storage before FETCH's DIE begins to  
operate on that data (in the relocation routine, in the computation  
of the next disk and main storage addresses, and in the changing of a  
NOP to a TIC so the channel program may continue without  
interruption), hence the "disabled bit spin" is embedded within the  
DIE, which exit FETCH passes as a parameter in the IOSB which, in  
turn, is passed as a parameter to the STARTIO macro (which, in turn,  
invokes IECIOSCN to start the I/O operation).

The design is such that, under most conditions, a single STARTIO  
macro can read (and relocate) an entire load module. And, as I/O  
operations are, in general, the second most time-consuming operation  
after GETMAIN and FREEMAIN, this elaborate design is justified.

FETCH's DIE did not work properly in the early releases of MVS,  
leading to FETCH operations missing many PCIs, and, hence taking many  
disk revolutions to load even relatively simple load modules.

CTC operations and the JESes use a DIE, too.