commit fe330fdd3568beb880465a0ee974c7913d73dfcb
author Nikos Nikoleris <nikos.nikoleris@arm.com> Sun Mar 18 22:07:30 2018 +0000
committer Nikos Nikoleris <nikos.nikoleris@arm.com> Fri Jun 22 17:39:16 2018 +0000
tree 014244ab7ae7b686709cbe0b078e7198ff4c8fa1
parent f4015a2c62e7cd8c169dae801e6d6901f40e1e40

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
Reviewed-on: https://gem5-review.googlesource.com/11018
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

src/mem/cache/base.cc

diff --git a/src/mem/cache/base.cc b/src/mem/cache/base.cc
index a510bac..8fd9ac2 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()) {
@@ -887,6 +893,8 @@
             pkt->setCacheResponding();
             blk->status &= ~BlkDirty;
         }
+    } else if (pkt->isClean()) {
+        blk->status &= ~BlkDirty;
     } else {
         assert(pkt->isInvalidate());
         invalidateBlock(blk);

src/mem/cache/cache.cc

diff --git a/src/mem/cache/cache.cc b/src/mem/cache/cache.cc
index ffd6081..9b16129 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();
@@ -716,13 +714,11 @@
                                  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