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

[Daniel D. Daugherty]

The official configurations are listed here:

http://java.sun.com/javase/6/webnotes/install/system-configurations.html

but I don't know how to translate the various Linux versions
into something that would help resolve this issue.

Dan



On 7/7/2010 4:56 PM, Daniel D. Daugherty wrote:
> Andrew,
>
> I concur that it is time to change the default value for this flag
> so thumbs up on the webrev.
>
> My only worry is about HSX-19 deliveries into JDK-Updates. I'll
> poke around and see if I can find a statement about the minimum
> Linux that is supported.
>
> The majority of the JVM/TI relevant tests are internal so those
> won't do you much good. If you push this change to
>
>     http://hg.openjdk.java.net/jdk7/hotspot-rt/hotspot
>
> a.k.a. RT_Baseline, I can keep an eye on the internal test results.
>
> Dan
>
>
> On 7/7/2010 11:33 AM, Andrew Haley wrote:
>> The evaluation says:
>>
>> "As the submitter notes the functionality exists but is disabled by
>> default. The user can easily enable it by specifying
>> -XX:+UseLinuxPosixThreadCPUClocks
>>
>> "The functionality was added for JDK 6 under CR 6200022 but there was
>> concern at the time about enabling it by default (those concerns are
>> not documented in 6200022).
>>
>> "Perhaps it is time to enable this feature by default?"
>>
>> I changed the default for this parameter to true.
>>
>> I tested this change on an older Linux system that does not have the
>> high-speed thread clock interface (Red Hat Enterprise Linux AS release
>> 4, kernel 2.6.9).  The test case still works, but slowly.
>>
>> On a more recent system (Fedora 12, kernel 2.6.31) the test case is
>> much speeded up.
>>
>> Is there any more testing that I should do?
>>
>> Patch at http://cr.openjdk.java.net/~aph/6888526/
>>
>> OK to push?
>>
>> Andrew.
>>   
>