Hi Lu, In the shared state when the block exists in the L2, theOwner is irrelevant. I believe that it will always be directory owned in this situation, but there may be a sequence of transactions where theOwner isn't set reset consistently.
In the owned state theOwner must always point to the L1 that is responsible for the last copy of the block within the CMP, regardless of the state of L2. If there is no such L1, you are not in the owned state (by definition). Jared Excerpts From "lu peng" <[email protected]>: Re: [Simflex] About Piranha Cache: "lu peng" <[email protected]> >Date: Tue, 07 Mar 2006 03:38:16 +0000 >To: [email protected], [email protected] >From: "lu peng" <[email protected]> >Subject: Re: [Simflex] About Piranha Cache > ><html><div style='background-color:'><DIV class=RTE> ><P>Hi, Jared,</P> ><P>How are you recenlty? Are there any case that the theOwner points to L1 (ei >ther L1I or L1D), but l2lookup hits and the PiranhaDir is in the Shared or Own >ed state? If so, in what situation?</P> ><P>Thanks,</P> ><P>Lu<BR><BR></P></DIV> ><DIV></DIV> ><BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #a0c6e5 2 >px solid; MARGIN-RIGHT: 0px"><FONT style="FONT-SIZE: 11px; FONT-FAMILY: tahoma >,sans-serif"> ><HR color=#a0c6e5 SIZE=1> > ><DIV></DIV>From: <I>"Jared C. Smolens" <[email protected]> >;</I><BR>To: <I>[email protected], [email protected]</I><BR>Su >bject: <I>Re: [Simflex] About Piranha Cache</I><BR>Date:   >;<I>Thu, 2 Feb 2006 12:07:30 -0500 (EST)</I><BR>>Hi Lu,<BR>><BR>>Yes, > the simulation model maintains a PiranhaDirEntry for every valid<BR>>line >in the CMP (in one or more L1s, L2, or both).<BR>><BR>>To fully determin >e where the line is, you need to consider its state,<BR>>it's owner, and th >e l2Lookup structure:<BR>><BR>>theOwner points to a cache which can supp >ly a coherent value for the<BR>>line.<BR>>For the Shared and Owner state >s, it's safe to read the L2 value if<BR>>l2Lookup shows a hit, since all co >pies of the line must be identical in<BR>>these states. If l2Loo >kup shows a miss, follow theOwner to the >correct<BR>>L1. For the Modified state, always follow theOwner ( >set to the core<BR>>index or -1 if the L2 owns the line).<BR>><BR>>Ja >red<BR>><BR></FONT></BLOCKQUOTE></div></html> > Jared Smolens ----------- Electrical and Computer Engineering www.rabidpenguin.org ------------- Carnegie Mellon University jsmolens AT ece.cmu.edu ------ HH A-313 ------ Pittsburgh, PA
