RFR(XS): 8193509: Test dynamic path to retrieve active processor count.

[Lindenmaier, Goetz]

Hi David, 

I implemented the test to detect iff the VM is run on an older OS 
than it was compiled on which lacks the CPU_ALLOC support.
Basically that's what I wrote into the @summary :)

I ran the test with jdk 9 on ppc64, ppc64le, s390, x86_64, 
SLES 11, 12; RHEL 6, 7 (not all combinations, though).  
Tonight it will run with jdk/hs and a similar coverage.  (Actually, the 
test has been in the test suite for the other platforms, too, but 
is skipped there, so skipping is tested, too.)

New webrev with renamed test:
http://cr.openjdk.java.net/~goetz/wr17/8193509-activeProcTest/webrev.02/

Best regards,
 Goetz.




> -----Original Message-----
> From: David Holmes [mailto:david.holmes at oracle.com]
> Sent: Donnerstag, 14. Dezember 2017 13:40
> To: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>; hotspot-runtime-
> dev at openjdk.java.net
> Subject: Re: RFR(XS): 8193509: Test dynamic path to retrieve active processor
> count.
> 
> Hi Goetz,
> 
> On 14/12/2017 10:06 PM, Lindenmaier, Goetz wrote:
> > Hi,
> >
> > active_processor_count() in os_linux.cpp has two paths, one is only
> > excercised if the VM runs on a machine with more than 1024 processors.
> > Flag UseCpuAllocPath allows to force this path. Add a test with
> > this flag to excercise this code.
> 
> Not sure I see the value in having a test for this. Where would this
> test run such that it would show us there is some problem that needs
> fixing? The real test of that code path is on a machine with > 1024
> processors.
> 
> That aside please reformat the
> 
>    29  * @summary If #processors > 1024 os_linux.cpp uses special
> coding. Excercise this by forcing usage of this coding. If this fails,
> this VM was either compiled on a platform which does not define
> CPU_ALLOC, or it is executed on a platform that does not support it.
> 
> to use multiple lines. Though a simple:
> 
> @summary  Test the UseCpuAllocPath code path
> 
> would suffice IMHO.
> 
> And the name of the test should more accurately be TestUseCpuAllocPath.
> 
> > Please review this change. I please need a sponsor. (Do I need one with
> the new repo setup?)
> > http://cr.openjdk.java.net/~goetz/wr17/8193509-
> activeProcTest/webrev.01/
> 
> The need for a sponsor is not related to the repo setup, but the need
> for adequate cross-platform testing. If the set of platforms you've
> tested on includes all the platforms Oracle would test on, then a
> sponsor would not add anything to the equation. But your RFR needs to
> include what testing you have done.
> 
> Thanks,
> David
> 
> > Best regards,
> >    Goetz.
> >