Nikos Nikoleris has submitted this change and it was merged. ( https://gem5-review.googlesource.com/5043 )

Change subject: mem: Align the snoop behavior in the XBar for atomic and timing
......................................................................

mem: Align the snoop behavior in the XBar for atomic and timing

When the XBar receives a Writeback/WriteClean packet, it doesn't need
to snoop the upstream caches. It only queries the snoop filter and
sets the blockCached flag accordingly. This is in line with the
recvTimingReq.

Change-Id: I0ae22f21491d75a111019124bb95bac7b16d3cd3
Reviewed-by: Andreas Sandberg <[email protected]>
Reviewed-by: Anouk Van Laer <[email protected]>
Reviewed-on: https://gem5-review.googlesource.com/5043
Reviewed-by: Jason Lowe-Power <[email protected]>
Maintainer: Nikos Nikoleris <[email protected]>
---
M src/mem/coherent_xbar.cc
1 file changed, 13 insertions(+), 3 deletions(-)

Approvals:
  Jason Lowe-Power: Looks good to me, approved
  Anouk Van Laer: Looks good to me, but someone else must approve
  Nikos Nikoleris: Looks good to me, approved



diff --git a/src/mem/coherent_xbar.cc b/src/mem/coherent_xbar.cc
index 7c3a4e3..ef06208 100644
--- a/src/mem/coherent_xbar.cc
+++ b/src/mem/coherent_xbar.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011-2016 ARM Limited
+ * Copyright (c) 2011-2017 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -661,8 +661,18 @@
             // between and change the filter state
snoopFilter->finishRequest(false, pkt->getAddr(), pkt->isSecure());

-            snoop_result = forwardAtomic(pkt, slave_port_id, InvalidPortID,
-                                         sf_res.first);
+            if (pkt->isEviction()) {
+                // for block-evicting packets, i.e. writebacks and
+                // clean evictions, there is no need to snoop up, as
+                // all we do is determine if the block is cached or
+                // not, instead just set it here based on the snoop
+                // filter result
+                if (!sf_res.first.empty())
+                    pkt->setBlockCached();
+            } else {
+ snoop_result = forwardAtomic(pkt, slave_port_id, InvalidPortID,
+                                             sf_res.first);
+            }
         } else {
             snoop_result = forwardAtomic(pkt, slave_port_id);
         }

--
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Gerrit-Project: public/gem5
Gerrit-Branch: master
Gerrit-MessageType: merged
Gerrit-Change-Id: I0ae22f21491d75a111019124bb95bac7b16d3cd3
Gerrit-Change-Number: 5043
Gerrit-PatchSet: 3
Gerrit-Owner: Nikos Nikoleris <[email protected]>
Gerrit-Reviewer: Andreas Sandberg <[email protected]>
Gerrit-Reviewer: Anouk Van Laer <[email protected]>
Gerrit-Reviewer: Jason Lowe-Power <[email protected]>
Gerrit-Reviewer: Nikos Nikoleris <[email protected]>
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