Review request 6983240: guarantee((Solaris::min_stack_allowed >= (StackYellowPages+StackRedPages...) wrong
coleen.phillimore at oracle.com
Wed Oct 6 10:55:25 PDT 2010
Can I get one more review?
webrev at http://cr.openjdk.java.net/~coleenp/6983240_2/
On 10/05/10 11:26, Coleen Phillimore wrote:
> Thanks David - some comments inline...
> On 10/04/10 20:41, David Holmes wrote:
>> Hi Coleen,
>> In os_solaris.cpp this comment should now refer to 2*BytesPerWord
>> // Add in BytesPerWord times page size to account for VM stack during
>> // class initialization depending on 32 or 64 bit VM.
>> That said this formulation (not your I know) is confusing. What does
>> bytesPerWord have to do with the amount of stack needed? Is this just
>> some weird way of getting twice the amount of stack on 64-bit as
>> 32-bit? Are the pages sizes even the same in that case?
> Yeah, I believe it's just to account for 64 vs. 32 bit. The page
> sizes are the same if 32 or 64 bit. I have
>> Also in os_solaris.cpp isn't this guarantee always false:
>> ! guarantee(os::Solaris::min_stack_allowed >= thr_min_stack(),
>> ! "need to increase min_stack_allowed");
> No, it doesn't assert, because in your next mail you found that
> thr_min_stack() is smaller than our min_stack_allowed. I could revert
> that change but min_stack_allowed() is for the VM to get initialized
> rather than this thr_min_stack() which is for the OS to initialize the
> thread. I would assume the latter is always smaller than the former
> or something is really wrong. Changing it back probably doesn't hurt
>> AFAICS min_stack_allowed is set to one of these values:
>> os::Solaris::min_stack_allowed = 128*K;
>> os::Solaris::min_stack_allowed = 96*K;
>> os::Solaris::min_stack_allowed = 224*K;
>> os::Solaris::min_stack_allowed = 64*K;
>> but the manpage for thr_min_stack states:
>> thr_min_stack() will return the unsigned int THR_MIN_STACK,
>> which is the minimum-allowable size for a thread's stack.
>> In this implementation the default size for a user-thread's
>> stack is one mega-byte.
>> 1MB > all the above. ???
>> Coleen Phillimore said the following on 10/05/10 08:45:
>>> Summary: min_stack_allowed is a compile time constant and
>>> Stack*Pages are settable
>>> Also stress tested various combinations of -Xss and
>>> -XX:StackShadowPages=n. This also fixes a bug
>>> 6346701: stack overflow in native method results in segfault, not a
>>> or rather it fixes the observed SEGVs with different settings of
>>> -Xss and -XX:StackShadowPages in the evaluation. We were getting
>>> stack overflow before the stack overflow exception was initialized,
>>> causing infinite recusion trying to initialize it.
>>> Also fixed a random g++ compilation error.
>>> open webrev at http://cr.openjdk.java.net/~coleenp/6983240/
>>> bug link at http://bugs.sun.com/view_bug.do?bug_id=6983240
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