RFR 8161696 [TESTBUG] runtime/StackGuardPages/testme.sh uses invalid argument -Xss328k

[frederic parain]

Hi Jerry,

On 26/07/2016 22:55, Gerald Thornbrugh wrote:
> Hi David,
>> Hi Jerry,
>>
>> On 27/07/2016 2:06 AM, Gerald Thornbrugh wrote:
>>> Hi Everyone,
>>>
>>> I would like to have the following change reviewed:
>>>
>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8161696
>>>
>>> Webrev:http://cr.openjdk.java.net/~gthornbr/8161696/hotspot-webrev.01/
>>> <http://cr.openjdk.java.net/%7Egthornbr/8161696/hotspot-webrev.01/>
>>>
>>> The stack size for this test needs to be increased to 384K for some
>>> platforms.
>>
>> Is there a specific reason we set -Xss in the first place instead of
>> just taking the platform defaults? If the platform stack settings
>> change this test may need updating again.
>
> It was my understand (maybe incorrectly) that setting -Xss was an
> attempt to limit the memory and time
> resources the test takes.  Using the smallest stack size allowable will
> allocate less memory and reduce the
> amount of time the test takes.  Since I think Fred wrote the test he
> would know better than I would.
>
> Fred, what is the reason behind specifying "-Xss" for this test?

I'm not the author of this test, but I can try to contribute my
two cents.

I'm not seeing any particular reason to limit the stack size to
320KB other than reducing time and resources required for this
test.

Looking at the test history, Dmitry did the current version of the
test, but the "-Xss320k" argument was already there before Dmitry
re-wrote the test to fix 8042155. So it looks like a relic from
old code for which the rational has been lost.

Regarding the test, limiting the stack size looks a good idea to
avoid wasting too much time and resources during testing. However,
I'm seeing to reason to make the stack size "as small as possible".
A 1MB stack size could already provide efficient improvement while
avoiding platform dependent stack size constraint (and I'll be
cursed for this by next generations of HotSpot developer as a
1MB limitation could become completely unjustified in the future).

Fred

> I have thought about the test harness setting an environment variable
> and/or a java property to the correct
> minimum values for "-Xss" depending upon the architecture the test is
> running on.  The tests could then use
> the value to start each test. That way each test could be tailored for
> the specific architecture. After looking into
> this it looks the implementation would be significant and would be
> outside the scope of this bug fix.
>
> Thanks,
>
> Jerry
>>
>> Thanks,
>> David
>>
>>> My fix for JDK-8081770 https://bugs.openjdk.java.net/browse/JDK-8081770
>>> moved the functionality
>>> from the testme.sh script to exeinvoke.c so the dependency for a local
>>> compiler could be removed.
>>> Because of this the stack size change needs to be applied to exeinvoke.c
>>> file instead of the testme.sh file.
>>>
>>> Please let me know if you have any questions or concerns.
>>>
>>> Thanks,
>>>
>>> Jerry
>