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authorAli Saidi <saidi@eecs.umich.edu>2011-09-13 12:58:08 -0400
committerAli Saidi <saidi@eecs.umich.edu>2011-09-13 12:58:08 -0400
commit649c239ceef2d107fae253b1008c6f214f242d73 (patch)
tree06edeb7bfa7b9d1e9167b9cb80f7f9600d41b9a0 /src/sim
parentbb921b1459ef3ec55f9cea4ac8d203cd3c801cfd (diff)
downloadgem5-649c239ceef2d107fae253b1008c6f214f242d73.tar.xz
LSQ: Only trigger a memory violation with a load/load if the value changes.
Only create a memory ordering violation when the value could have changed between two subsequent loads, instead of just when loads go out-of-order to the same address. While not very common in the case of Alpha, with an architecture with a hardware table walker this can happen reasonably frequently beacuse a translation will miss and start a table walk and before the CPU re-schedules the faulting instruction another one will pass it to the same address (or cache block depending on the dendency checking). This patch has been tested with a couple of self-checking hand crafted programs to stress ordering between two cores. The performance improvement on SPEC benchmarks can be substantial (2-10%).
Diffstat (limited to 'src/sim')
-rw-r--r--src/sim/faults.cc6
-rw-r--r--src/sim/faults.hh10
2 files changed, 16 insertions, 0 deletions
diff --git a/src/sim/faults.cc b/src/sim/faults.cc
index 3f1369bcc..bd05df834 100644
--- a/src/sim/faults.cc
+++ b/src/sim/faults.cc
@@ -56,6 +56,12 @@ void UnimpFault::invoke(ThreadContext * tc, StaticInstPtr inst)
panic("Unimpfault: %s\n", panicStr.c_str());
}
+void ReExec::invoke(ThreadContext *tc, StaticInstPtr inst)
+{
+ tc->pcState(tc->pcState());
+}
+
+
#if !FULL_SYSTEM
void GenericPageTableFault::invoke(ThreadContext *tc, StaticInstPtr inst)
{
diff --git a/src/sim/faults.hh b/src/sim/faults.hh
index 7f431b313..f5e9aded1 100644
--- a/src/sim/faults.hh
+++ b/src/sim/faults.hh
@@ -75,6 +75,16 @@ class UnimpFault : public FaultBase
StaticInstPtr inst = StaticInst::nullStaticInstPtr);
};
+class ReExec : public FaultBase
+{
+ public:
+ virtual FaultName name() const { return "Re-execution fault";}
+ ReExec() {}
+ void invoke(ThreadContext *tc,
+ StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+};
+
+
#if !FULL_SYSTEM
class GenericPageTableFault : public FaultBase
{