Request for review: 6888526 Linux getCurrentThreadCpuTime is drastically slower than Windows

[Daniel D. Daugherty]

On 7/8/2010 2:57 PM, David Holmes wrote:
> Andrew Haley said the following on 07/09/10 02:49:
>>> Further, as Dan mentions, this would then affect Java 6 updates and 
>>> that
>>> is not allowed (without additional 'paperwork') so we'd have to augment
>>> Arguments::parse_each_vm_init_arg in arguments.cpp by adding to the 
>>> end:
>>>
>>>  if (JDK_Version::current().compare_major(6) <= 0 &&
>>>       FLAG_IS_DEFAULT(UseLinuxPosixThreadCPUClocks)) {
>>>     FLAG_SET_DEFAULT(UseLinuxPosixThreadCPUClocks, false);
>>>   }
>>>
>>> this forces the flag to false in Java 6 unless it has been set 
>>> explicitly.
>>
>> New webrev at http://cr.openjdk.java.net/~aph/6888526-2/
>>
>> I enclosed the JDK version test in #ifdef LINUX because I don't think
>> the UseLinuxPosixThreadCPUClocks flag exists in other systems.
>
> Right. Thumbs up from me too.
>
> Dan: do you know what test results we'd need to watch for any issues 
> this change introduces (ie buggy CPU clocks) ?

Not off the top of my head...

Dan