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From "Weldon Washburn" <weldon...@gmail.com>
Subject Re: [drlvm][gc/threading] need the two lsb's from object header for MMTk port
Date Fri, 06 Oct 2006 20:33:26 GMT
Artem,
I'd like to confirm what you said. For GC_BIT_MASK, it looks like the bottom
two bits of byte number one is available for exclusive GC use.  If the GC
needs to alter these two bits while the mutator(s) are running, the GC needs
to use CAS on the entire 32 bits of obj_info.  Does this sound right?

  Thanks
       Weldon


On 10/6/06, Artem Aliev <artem.aliev@gmail.com> wrote:
>
> Weldon, All
>
> // the TM monitor implementation bits.
> // 11111111 11111111 11111100 00000000
> #define LOCKWORD_MASK (0xffffffff ^ 0x3FF)
> // THREAD_ID
> #define THREAD_ID_MASK (0xffff0000)
>
>
> // 6bit default hashcode
> // 00000000 00000000 00000000 01111110
> // custom hashcode algorithm could free these bits
> #define HASH_MASK 0x7e
>
> // free bits for GC usage
> // 00000000 00000000 00000011 10000001
> #define GC_BIT_MASK (0xffffffff ^ (LOCKWORD_MASK | HASH_MASK))
>
>
> Thanks
> Artem
> --
> Weldon Washburn
> Intel Middleware Products Division

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