Re: [Gems-users] Question about MOSI_SMP_directory_1level

[Mike Marty <mikem@xxxxxxxxxxx>]

This classic race is definitely handled by the protocol.

I believe that when the PUTX arrives in step (4) below, it is triggered as
a PUTX_old event instead of a PUTX.

--Mike


>    I have been modifying this protocol and have noticed a rare race
> condition which I do not think it handles.  In particular it happens like
> this:
>
> 1) Owner issues PUTX due to a cache replacement
> 2) Before this arrives at the directory a gets (or getx) is forwarded to
> the owner by the directory
> 3) The directory then responds to the PUTX
> 4) The response to the PUTX arrives at the owner first, transitioning the
> state to Invalid
> 5) The forwarded GETS arrives.
>
> Is this handled somewhere I am not seeing, or is this a genuine issue with
> this protocol?
>
> Sean
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