On 23/3/23 01:03, René Jansen wrote:
That's another interesting take; but I have to be sure that it is used before I
declare the winner.
I stand corrected. I just read the hardware specs. DFP was originally
implemented in millicode (vertical microcode) on the z9 but has been on
the hardware in a DFP unit since z10.
FYI, the OpenJ9 JIT can implement JIT intrinsics to generate native
decimal instructions when running on z/OS. IBM have open source OpenJ9
and OMR so you can snoop around the code
https://github.com/eclipse-openj9/openj9/blob/master/jcl/src/openj9.dataaccess/share/classes/com/ibm/dataaccess/DecimalData.java
On 22 Mar 2023, at 18:00, David Crayford <dcrayf...@gmail.com> wrote:
I can't answer you original question but I doubt if DFP is really that much
faster. I would imagine it's implemented in millicode and not silicone so is a
software implementation at heart. I would be surprised if it beats BigDecimal
on a PC but I could be wrong.
On 23/3/23 00:42, René Jansen wrote:
Without reading any documentation (sorry!), the issue at hand is this. I want
to show the performance gains of using DFP (Decimal Floating Point) for the
typical financial application, after I noticed at some other client their
bought packages seldom were compiled using the right compiler options (some
could have run in 1966 or so - well I exaggerate, but a Z9 would not have been
a problem).
This is for Java applications, and it proves slightly harder than I thought. I
don’t have object modules to disassemble and while I can do
-XX:+UnlockDiagnosticVMOptions -XX:+PrintAssembly on my mac or any Linux box,
IBM’s J9 seems to ignore these altogether. For Linux and the mac there is a .so
(or .dylib) that even disassembles what you’d otherwise are shown in hex -
https://chriswhocodes.com/hsdis/ which is called hsdis but what I would not
upload to other people’s machines lightly without building it myself.
Does anybody know how to ask the J9 (Java 8) on z/OS how to show me what it
does when the JIT decides native code would be best?
many thanks in advance,
best regards,
René Jansen.
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