=========================================================== -----Original Message----- From: "McKown, John" <[EMAIL PROTECTED]> Sent: 7/19/2006 11:58 AM To: "IBM-MAIN@BAMA.UA.EDU" <IBM-MAIN@BAMA.UA.EDU> Subject: Re: Why is zSeries so CPU poor?
> -----Original Message----- > From: IBM Mainframe Discussion List > [mailto:[EMAIL PROTECTED] On Behalf Of Edward Jaffe > Sent: Wednesday, July 19, 2006 12:48 PM > To: IBM-MAIN@BAMA.UA.EDU > Subject: Re: Why is zSeries so CPU poor? > > > Kuredjian, Michael wrote: > > Does IBM make a co-processor add-in that can provide an > assist for the JVM overhead? > > > > zAAPs Except that a zAAP is not really a Java CPU. It is a regular CPU, with some microcode changes to remove specific abilities. From what little I can gather, it is actually the z/OS dispatcher, in conjunction with the Java JVM, which restricts the zAAP from doing any non-Java "general purpose" work. It might be "interesting" to actually somehow have an Opteron, pSeries, or Xeon processor in the zSeries frame with some sort of "interconnect" so that the code on the zSeries could run those instruction. A terror to program, I'd bet. But technically interesting (to me at least). I would love to get a peek at one of those. I wonder how long it might be for somebody to figure out what "magic" the JVM does to mark its work a "zAAP capable" to the z/OS dispatcher so that non-Java work could run on it. Of course, I would bet that doing this would be a violation of the T&Cs for the processor. Also, I'll bet that there is some sneaky code in z/OS to try to detect this. E.g. if the program does an SVC or PC or ???, then an abend occurs instead of actually doing the function desired. I know that I'd certainly put those checks in. -- John McKown =========================================================== I doubt that IBM could remove generally documented machine instructions or system services. The JVM is allowed to call JNI (Java Native Interface) routines, written in any language (usually C), which are allowed by definition to use any operating system services and any machine dependent features. Jeffrey D. Smith Farsight Systems Corporation 24 BURLINGTON DR LONGMONT, CO 80501 303-774-9381 direct 303-709-8153 cell 303-484-6170 fax ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
