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

[David Holmes]

Hi Goetz,

On 14/12/2017 11:01 PM, Lindenmaier, Goetz wrote:
> 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 :)

So do you plan on running the test on such older OS? And on such an OS 
will you ever find >1024 processors and so try to really take the path 
that test shows is not usable ?

> 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/

Okay. I'll apply it locally and run on our systems just for a sanity 
check. Meanwhile a second reviewer is needed.

Thanks,
David

> 
> 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.
>>>