commit 12641069de95fe7c6bfff0d76e547b65ef3589a2
author Tiago Mück <tiago.muck@arm.com> Wed Mar 02 16:17:43 2022 -0600
committer Tiago Muck <tiago.muck@arm.com> Wed Jun 01 15:23:47 2022 +0000
tree 04a35b8d4ea9e0b2d379fc2e0d412e6a6e5b2e50
parent d1d6b4cb9ed018d1b6f5aa11e0a8d287bd4ddfe3

mem-ruby: reuse existing event on CleanUnique

Reuse the existing MaintainCoherence event to schedule
writebacks or cache fill after a CleanUnique.

JIRA: https://gem5.atlassian.net/browse/GEM5-1195

Change-Id: I127ebf78736b8312ccf2b18cf7c586eb5a77f373
Signed-off-by: Tiago Mück <tiago.muck@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/57393
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/mem/ruby/protocol/chi/CHI-cache-actions.sm

diff --git a/src/mem/ruby/protocol/chi/CHI-cache-actions.sm b/src/mem/ruby/protocol/chi/CHI-cache-actions.sm
index d11b6e7..6fa13cb 100644
--- a/src/mem/ruby/protocol/chi/CHI-cache-actions.sm
+++ b/src/mem/ruby/protocol/chi/CHI-cache-actions.sm
@@ -690,43 +690,28 @@
     tbe.updateDirOnCompAck := false;
     assert(tbe.dataValid == false);
     assert(tbe.is_stale);
+    tbe.is_stale := false;
     tbe.actions.push(Event:SendCompUCRespStale);
     tbe.actions.push(Event:WaitCompAck);
-    tbe.is_stale := false;
+    tbe.actions.push(Event:TagArrayWrite);
   } else {
     // must be the only one in sharers map
     assert(tbe.dir_sharers.count() == 1);
     assert(tbe.dataUnique);
 
-    tbe.actions.push(Event:SendCompUCResp);
-    tbe.actions.push(Event:WaitCompAck);
-
-    // similar to Initiate_MaitainCoherence; writeback if the owner has data as
-    // clean data and we have it dirty and cannot keep it
-    bool fill_pipeline := tbe.dataValid && tbe.dataDirty;
-    bool req_has_dirty := tbe.dir_ownerExists && (tbe.dir_owner == tbe.requestor);
-    if (tbe.dataValid && tbe.dataDirty && tbe.dataToBeInvalid &&
-        (req_has_dirty == false)) {
-      fill_pipeline := false;
-      if (is_HN) {
-        tbe.actions.push(Event:SendWriteNoSnp);
-      } else {
-        tbe.actions.push(Event:SendWriteClean);
-      }
-      tbe.actions.push(Event:WriteBEPipe);
-      tbe.actions.push(Event:SendWBData);
-    }
-
     // needed by UpdateDirState_FromReqResp triggered by the expected CompAck
     tbe.dataMaybeDirtyUpstream := true;
     tbe.requestorToBeExclusiveOwner := true;
     tbe.dir_ownerExists := false;
 
-    if (fill_pipeline) {
-      tbe.actions.push(Event:CheckCacheFill);
-    }
+    tbe.actions.push(Event:SendCompUCResp);
+    tbe.actions.push(Event:WaitCompAck);
+
+    // Ensure we writeback or update the cache if the owner has data as
+    // clean data and we have it dirty.
+    // MaintainCoherence queues the TagArrayWrite
+    tbe.actions.push(Event:MaintainCoherence);
   }
-  tbe.actions.push(Event:TagArrayWrite);
 }