[gem5-dev] Change in gem5/gem5[master]: mem-cache: Promote deferred targets on cache clean responses

[Nikos Nikoleris (Gerrit)]

Nikos Nikoleris has uploaded this change for review. (  
https://gem5-review.googlesource.com/11018

Change subject: mem-cache: Promote deferred targets on cache clean responses
......................................................................

mem-cache: Promote deferred targets on cache clean responses

While a cache clean operation is pending, all requests to the
corresponding block get deferred. When the response of a cache clean
operation is received, if the block is present and the response is not
invalidating, we can service all deferred targets that didn't require
writable. This change implements this functionality.

Change-Id: Ief47e74d07749a6a9736ab450eb46eefa53464a2
---
M src/mem/cache/base.cc
M src/mem/cache/cache.cc
2 files changed, 10 insertions(+), 6 deletions(-)



diff --git a/src/mem/cache/base.cc b/src/mem/cache/base.cc
index a8f29e3..80fb698 100644
--- a/src/mem/cache/base.cc
+++ b/src/mem/cache/base.cc
@@ -491,6 +491,12 @@
         // The block was marked not readable while there was a pending
         // cache maintenance operation, restore its flag.
         blk->status |= BlkReadable;
+
+        // This was a cache clean operation (without invalidate)
+        // and we have a copy of the block already. Since there
+        // is no invalidation, we can promote targets that don't
+        // require a writable copy
+        mshr->promoteReadable();
     }

     if (blk && blk->isWritable() && !pkt->req->isCacheInvalidate()) {
@@ -873,6 +879,8 @@
             pkt->setCacheResponding();
             blk->status &= ~BlkDirty;
         }
+    } else if (pkt->isClean()) {
+        blk->status &= ~BlkDirty;
     } else {
         assert(pkt->isInvalidate());
         invalidateBlock(blk);
diff --git a/src/mem/cache/cache.cc b/src/mem/cache/cache.cc
index 34f3dc5..f2b1585 100644
--- a/src/mem/cache/cache.cc
+++ b/src/mem/cache/cache.cc
@@ -674,8 +674,6 @@
     const int initial_offset = initial_tgt->pkt->getOffset(blkSize);

     const bool is_error = pkt->isError();
-    bool is_fill = !mshr->isForward &&
-        (pkt->isRead() || pkt->cmd == MemCmd::UpgradeResp);
     // allow invalidation responses originating from write-line
     // requests to be discarded
     bool is_invalidate = pkt->isInvalidate();
@@ -717,13 +715,11 @@
                                  targets.allocOnFill);
                 assert(blk);

-                // treat as a fill, and discard the invalidation
-                // response
-                is_fill = true;
+                // discard the invalidation response
                 is_invalidate = false;
             }

-            if (is_fill) {
+            if (blk && blk->isValid() && !mshr->isForward) {
                 satisfyRequest(tgt_pkt, blk, true,  
mshr->hasPostDowngrade());

                 // How many bytes past the first request is this one

--
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Gerrit-Project: public/gem5
Gerrit-Branch: master
Gerrit-Change-Id: Ief47e74d07749a6a9736ab450eb46eefa53464a2
Gerrit-Change-Number: 11018
Gerrit-PatchSet: 1
Gerrit-Owner: Nikos Nikoleris <nikos.nikole...@arm.com>
Gerrit-MessageType: newchange
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