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authorAndreas Sandberg <Andreas.Sandberg@ARM.com>2014-10-16 05:49:40 -0400
committerAndreas Sandberg <Andreas.Sandberg@ARM.com>2014-10-16 05:49:40 -0400
commit76b0ff9ecd8bd4818dff8a3cc811bee547b643b4 (patch)
treed59cdf33b5f0109ef7ead33e81ed5c95aee423f8
parent3697990c27243f0c454f2fab0f12ed06759c97b9 (diff)
downloadgem5-76b0ff9ecd8bd4818dff8a3cc811bee547b643b4.tar.xz
cpu: Add branch predictor PMU probe points
This changeset adds probe points that can be used to implement PMU counters for branch predictor stats. The following probes are supported: * BPRedUnit::ppBranches / Branches * BPRedUnit::ppMisses / Misses
-rw-r--r--src/cpu/pred/bpred_unit.hh31
-rw-r--r--src/cpu/pred/bpred_unit_impl.hh20
2 files changed, 51 insertions, 0 deletions
diff --git a/src/cpu/pred/bpred_unit.hh b/src/cpu/pred/bpred_unit.hh
index bca64cce0..851cdbb78 100644
--- a/src/cpu/pred/bpred_unit.hh
+++ b/src/cpu/pred/bpred_unit.hh
@@ -56,6 +56,7 @@
#include "cpu/inst_seq.hh"
#include "cpu/static_inst.hh"
#include "params/BranchPredictor.hh"
+#include "sim/probe/pmu.hh"
#include "sim/sim_object.hh"
/**
@@ -76,6 +77,8 @@ class BPredUnit : public SimObject
*/
void regStats();
+ void regProbePoints() M5_ATTR_OVERRIDE;
+
/** Perform sanity checks after a drain. */
void drainSanityCheck() const;
@@ -290,6 +293,34 @@ class BPredUnit : public SimObject
Stats::Scalar usedRAS;
/** Stat for number of times the RAS is incorrect. */
Stats::Scalar RASIncorrect;
+
+ protected:
+ /**
+ * @{
+ * @name PMU Probe points.
+ */
+
+ /**
+ * Helper method to instantiate probe points belonging to this
+ * object.
+ *
+ * @param name Name of the probe point.
+ * @return A unique_ptr to the new probe point.
+ */
+ ProbePoints::PMUUPtr pmuProbePoint(const char *name);
+
+
+ /**
+ * Branches seen by the branch predictor
+ *
+ * @note This counter includes speculative branches.
+ */
+ ProbePoints::PMUUPtr ppBranches;
+
+ /** Miss-predicted branches */
+ ProbePoints::PMUUPtr ppMisses;
+
+ /** @} */
};
#endif // __CPU_PRED_BPRED_UNIT_HH__
diff --git a/src/cpu/pred/bpred_unit_impl.hh b/src/cpu/pred/bpred_unit_impl.hh
index 53ec808b6..4d17bfd33 100644
--- a/src/cpu/pred/bpred_unit_impl.hh
+++ b/src/cpu/pred/bpred_unit_impl.hh
@@ -119,6 +119,22 @@ BPredUnit::regStats()
;
}
+ProbePoints::PMUUPtr
+BPredUnit::pmuProbePoint(const char *name)
+{
+ ProbePoints::PMUUPtr ptr;
+ ptr.reset(new ProbePoints::PMU(getProbeManager(), name));
+
+ return ptr;
+}
+
+void
+BPredUnit::regProbePoints()
+{
+ ppBranches = pmuProbePoint("Branches");
+ ppMisses = pmuProbePoint("Misses");
+}
+
void
BPredUnit::drainSanityCheck() const
{
@@ -141,6 +157,7 @@ BPredUnit::predict(const StaticInstPtr &inst, const InstSeqNum &seqNum,
TheISA::PCState target = pc;
++lookups;
+ ppBranches->notify(1);
void *bp_history = NULL;
@@ -259,6 +276,8 @@ BPredUnit::predictInOrder(const StaticInstPtr &inst, const InstSeqNum &seqNum,
TheISA::PCState target;
++lookups;
+ ppBranches->notify(1);
+
DPRINTF(Branch, "[tid:%i] [sn:%i] %s ... PC %s doing branch "
"prediction\n", tid, seqNum,
inst->disassemble(instPC.instAddr()), instPC);
@@ -438,6 +457,7 @@ BPredUnit::squash(const InstSeqNum &squashed_sn,
History &pred_hist = predHist[tid];
++condIncorrect;
+ ppMisses->notify(1);
DPRINTF(Branch, "[tid:%i]: Squashing from sequence number %i, "
"setting target to %s.\n", tid, squashed_sn, corrTarget);