Speculative Data Cache

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+
+<p style="text-align: justify;" class="MsoNormal"><span style=
+"font-size: 10pt;"><span style="">   </span> This cache implements the
+write-back policy. A new “Speculative” state is added to each line. This allows
+the cache to differentiate cache blocks that was written after a checkpoint was
+taken. If a speculative block has to be evicted, the corresponding block in the
+next lower hierarchy will be marked as “Speculative”.</span></p>
+<p style="text-align: justify;" class="MsoNormal"><span style=
+"font-size: 10pt;"><span style="">   </span> However if the following level is
+the main memory or a normal cache, then the checkpoint will be discarded and
+all blocks in “Speculative” state will be changed to “Dirty”. This effectively
+commits all operations after a checkpoint. On the event of a rollback, every
+speculative cache block will be invalidated.</span></p>
+<p style="text-align: justify;" class="MsoNormal"><span style=
+"font-size: 10pt;"><span style="">   </span> The proposed design allows quick
+checkpoint taking. On the other hand, rolling back or committing a checkpoint
+is very expensive because a full traversal of the cache is needed.</span></p>