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From "Rana Dasgupta" <rdasg...@gmail.com>
Subject Re: [drlvm][reliability tests] Harmony-2986, Dekker's algorithm -- is this a valid test for modern SMP hardware?
Date Wed, 21 Feb 2007 18:47:42 GMT
Weldon,
  But I am not sure why the behavior would be different from J9 on the same
hardware. Do we jit volatiles differently?

Rana


On 2/20/07, Weldon Washburn <weldonwjw@gmail.com> wrote:
>
> It seems Dekker's algorithm is not expected to work on SPARC or IA32 SMP
> boxes unless memory fences are used.  DekkerTest.java in Harmony-2986 does
> not contain memory fences.  The volatile keyword guarantees the compiler
> will write a given variable to memory.  However, the HW may actually have
> a
> write buffer and allow reads to pass writes.  As far as I know, the Java
> language does not provide a means to invoke a memory fence.  Thus there is
> no way to fix up DekkerTest.java.  I may be misunderstanding something
> here.  Does anyone have comment?
>
> An excellent description of the issues involved is in a David Dice
> presentation at:
>
> http://blogs.sun.com/dave/resource/synchronization-public2.pdf
>
> --
> Weldon Washburn
> Intel Enterprise Solutions Software Division
>

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