even addr device: read data device even+1 device: write data device some other address: data transfer device
hipersockets and osa qdio both utilize the qdio protocol. I like to think of the qdio protocol as using whats good about I/Os (starting and interrupts) while not actually using I/O to transfer the data. The data transfer is through memory to memory protocol. The protocol is aware when there is data to push or pull, a pseudo interrupt. Since its mem-a-mem it is really fast and can support large buffers. Further, hipersockets use I/O def's and an IQD type chpid, but nothing gets plugged in or connected physically. z/VM maintained shops seem to like to give 256 devices per IQD chpid while z/OS shops seem much stingier, often giving some number like 16. David Kreuter -----Original Message----- From: The IBM z/VM Operating System on behalf of Bjoern A. Zeeb Sent: Mon 1/14/2008 6:22 PM To: [email protected] Subject: Re: [IBMVM] Hipersockets On Mon, 14 Jan 2008, Alan Altmark wrote: Hi, > Because a host requires 3 devices (subchannels) to connect to a > HiperSocket, ... Why does it need 3 SCs, as in what is the third for? Is there some (low level) documentation on this? /bz -- Bjoern A. Zeeb bzeeb at Zabbadoz dot NeT Software is harder than hardware so better get it right the first time.
