Poor man's profiler: add support for cache hit/miss

This is still very basic profiling, but it seems to get the work done.

diff --git a/src/support/pmprof.h b/src/support/pmprof.h
index fe5ab7a4fdde0466c3460e8acb7f021c96221bf6..8aa269a6a8ce6f1012a6c4de85bfdd2cb785b4e4 100644 (file)
--- a/src/support/pmprof.h
+++ b/src/support/pmprof.h
@@ -8,7 +8,8 @@
  * Full author contact details are available in file CREDITS.
  */
 
-/** How to use this trivial profiler:
+/**
+ * ==== HOW TO USE THIS TRIVIAL PROFILER:
  *
  * * at the beginning of the interesting block, just add:
  *   PROFILE_THIS_BLOCK(some_identifier)
@@ -17,7 +18,18 @@
  *
  * * when the program ends, statistics will be sent to standard error, like:
  *
- *   ##### some_identifier: 6.48475usec, count=25405
+ *   #pmprof# some_identifier: 6.51usec, count=7120, total=46.33msec
+ *
+ * * It is also possible to profile caching schemes. All it takes is an additional
+ *   PROFILE_CACHE_MISS(some_identifier)
+ *   in the place that takes care of cache misses. Then the output at the end will change to
+ *
+ *   #pmprof# some_identifier: 6.51usec, count=7120, total=46.33msec
+ *      hit: 96%, 4.36usec, count=6849, total=29.89msec
+ *     miss: 3%, 60.65usec, count=271, total=16.43msec
+ *
+ *
+ * ==== ABOUT PROFILING SCOPE:
  *
  * The code measured by the profiler corresponds to the lifetime of a
  * local variable declared by the PROFILE_THIS_BLOCK macro.
@@ -120,38 +132,66 @@ int gettimeofday(struct timeval * tv, struct timezone * /*tz*/)
 
 #endif // _WIN32
 
+namespace {
+
+void dump(long long sec, long long usec, unsigned long long count) {
+       double const total = sec * 1000000 + usec;
+       std::cerr << std::fixed << std::setprecision(2)
+                         << total / count
+                         << "usec, count=" << count
+                         << ", total=" << total * 0.001 << "msec"
+                         << std::endl;
+}
+
+}
+
+
 /* Helper class for gathering data. Instantiate this as a static
  * variable, so that its destructor will be executed when the program
  * ends.
  */
 
+
 class PMProfStat {
 public:
-       PMProfStat(char const * name)
-         : name_(name), sec_(0), usec_(0), count_(0) {}
+       PMProfStat(char const * name) : name_(name), sec_(0), usec_(0), count_(0),
+                                    miss_sec_(0), miss_usec_(0), miss_count_(0) {}
 
        ~PMProfStat() {
                if (count_>0) {
-                       double total = 0.001 * (sec_ * 1000000 + usec_);
-                       std::cerr << std::fixed << std::setprecision(2) 
-                               << "#pmprof# " << name_ << ": "
-                               << total / count_
-                               << "msec, count=" << count_
-                               << ", total=" << total << "msec"
-                               << std::endl;
+                       if (miss_count_ == 0) {
+                               std::cerr << "#pmprof# " << name_ << ": ";
+                               dump(sec_, usec_, count_);
+                       }
+                       else {
+                               std::cerr << "#pmprof# " << name_ << ": ";
+                               dump(sec_ + miss_sec_, usec_ + miss_usec_, count_ + miss_count_);
+                               std::cerr << "   hit: " << 100 * count_ / (count_ + miss_count_) << "%, ";
+                               dump(sec_, usec_, count_);
+                               std::cerr << "  miss: " << 100 * miss_count_ / (count_ + miss_count_) << "%, ";
+                               dump(miss_sec_, miss_usec_, miss_count_);
+                       }
                }
        }
 
-       void add(const long long s, const long long u) {
-               sec_ += s;
-               usec_ += u;
-               count_++;
+       void add(const long long s, const long long u, const bool hit) {
+               if (hit) {
+                       sec_ += s;
+                       usec_ += u;
+                       count_++;
+               } else {
+                       miss_sec_ += s;
+                       miss_usec_ += u;
+                       miss_count_++;
+               }
        }
 
 private:
        char const * name_;
        long long sec_, usec_;
        unsigned long long count_;
+       long long miss_sec_, miss_usec_;
+       unsigned long long miss_count_;
 };
 
 
@@ -162,7 +202,7 @@ private:
  */
 class PMProfInstance {
 public:
-       PMProfInstance(PMProfStat * stat) : stat_(stat)
+       PMProfInstance(PMProfStat * stat) : hit(true), stat_(stat)
        {
                gettimeofday(&before_, 0);
        }
@@ -170,9 +210,11 @@ public:
        ~PMProfInstance() {
                gettimeofday(&after_, 0);
                stat_->add(after_.tv_sec - before_.tv_sec,
-                          after_.tv_usec - before_.tv_usec);
+                          after_.tv_usec - before_.tv_usec, hit);
        }
 
+       bool hit;
+
 private:
        timeval before_, after_;
        PMProfStat * stat_;
@@ -183,5 +225,8 @@ private:
        static PMProfStat PMPS_##a(#a);\
        PMProfInstance PMPI_##a(&PMPS_##a);
 
+#define PROFILE_CACHE_MISS(a) \
+       PMPI_##a.hit = false;
+
 
 #endif