Review request 6983240: guarantee((Solaris::min_stack_allowed >= (StackYellowPages+StackRedPages...) wrong
vladimir.kozlov at oracle.com
Wed Oct 6 11:19:13 PDT 2010
Looks good for me.
Coleen Phillimore wrote:
> 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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