mem: Parameterize coherent xbar sanity checks

Parameters can be used to change coherent xbar limits for the routing
table and outstanding snoops. We need the ability to tweak these values
as the current defaults may be violated in simulations with large core
counts.

Change-Id: Idb64b8c105683d02d8beba5bce13b815181ba824
Signed-off-by: Tiago Muck <tiago.muck@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18789
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

3 files changed, 31 insertions, 9 deletions

diff --git a/src/mem/XBar.py b/src/mem/XBar.py
index 976a290eb..dab961fed 100644
--- a/src/mem/XBar.py
+++ b/src/mem/XBar.py
@@ -1,4 +1,4 @@
-# Copyright (c) 2012, 2015, 2017 ARM Limited
+# Copyright (c) 2012, 2015, 2017, 2019 ARM Limited
 # All rights reserved.
 #
 # The license below extends only to copyright in the software and shall
@@ -101,6 +101,12 @@ class CoherentXBar(BaseXBar):
     # An optional snoop filter
     snoop_filter = Param.SnoopFilter(NULL, "Selected snoop filter")
 
+    # Maximum number of outstanding snoop requests for sanity checks
+    max_outstanding_snoops = Param.Int(512, "Max. outstanding snoops allowed")
+
+    # Maximum routing table size for sanity checks
+    max_routing_table_size = Param.Int(512, "Max. routing table size")
+
     # Determine how this crossbar handles packets where caches have
     # already committed to responding, by establishing if the crossbar
     # is the point of coherency or not.
diff --git a/src/mem/coherent_xbar.cc b/src/mem/coherent_xbar.cc
index 839d95b9d..74c93be0f 100644
--- a/src/mem/coherent_xbar.cc
+++ b/src/mem/coherent_xbar.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011-2018 ARM Limited
+ * Copyright (c) 2011-2019 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -59,6 +59,8 @@
 CoherentXBar::CoherentXBar(const CoherentXBarParams *p)
     : BaseXBar(p), system(p->system), snoopFilter(p->snoop_filter),
       snoopResponseLatency(p->snoop_response_latency),
+      maxOutstandingSnoopCheck(p->max_outstanding_snoops),
+      maxRoutingTableSizeCheck(p->max_routing_table_size),
       pointOfCoherency(p->point_of_coherency),
       pointOfUnification(p->point_of_unification)
 {
@@ -325,8 +327,9 @@ CoherentXBar::recvTimingReq(PacketPtr pkt, PortID slave_port_id)
                 outstandingSnoop.insert(pkt->req);
 
                 // basic sanity check on the outstanding snoops
-                panic_if(outstandingSnoop.size() > 512,
-                         "Outstanding snoop requests exceeded 512\n");
+                panic_if(outstandingSnoop.size() > maxOutstandingSnoopCheck,
+                         "%s: Outstanding snoop requests exceeded %d\n",
+                         name(), maxOutstandingSnoopCheck);
             }
 
             // remember where to route the normal response to
@@ -334,8 +337,9 @@ CoherentXBar::recvTimingReq(PacketPtr pkt, PortID slave_port_id)
                 assert(routeTo.find(pkt->req) == routeTo.end());
                 routeTo[pkt->req] = slave_port_id;
 
-                panic_if(routeTo.size() > 512,
-                         "Routing table exceeds 512 packets\n");
+                panic_if(routeTo.size() > maxRoutingTableSizeCheck,
+                         "%s: Routing table exceeds %d packets\n",
+                         name(), maxRoutingTableSizeCheck);
             }
 
             // update the layer state and schedule an idle event
@@ -401,8 +405,9 @@ CoherentXBar::recvTimingReq(PacketPtr pkt, PortID slave_port_id)
                 assert(routeTo.find(pkt->req) == routeTo.end());
                 routeTo[pkt->req] = slave_port_id;
 
-                panic_if(routeTo.size() > 512,
-                         "Routing table exceeds 512 packets\n");
+                panic_if(routeTo.size() > maxRoutingTableSizeCheck,
+                         "%s: Routing table exceeds %d packets\n",
+                         name(), maxRoutingTableSizeCheck);
             }
         }
     }
diff --git a/src/mem/coherent_xbar.hh b/src/mem/coherent_xbar.hh
index ff28cb743..386b479f7 100644
--- a/src/mem/coherent_xbar.hh
+++ b/src/mem/coherent_xbar.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011-2015, 2017 ARM Limited
+ * Copyright (c) 2011-2015, 2017, 2019 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -278,8 +278,19 @@ class CoherentXBar : public BaseXBar
       * broadcast needed for probes.  NULL denotes an absent filter. */
     SnoopFilter *snoopFilter;
 
+    /** Cycles of snoop response latency.*/
     const Cycles snoopResponseLatency;
+
+    /** Maximum number of outstading snoops sanity check*/
+    const unsigned int maxOutstandingSnoopCheck;
+
+    /** Maximum routing table size sanity check*/
+    const unsigned int maxRoutingTableSizeCheck;
+
+    /** Is this crossbar the point of coherency? **/
     const bool pointOfCoherency;
+
+    /** Is this crossbar the point of unification? **/
     const bool pointOfUnification;
 
     /**