GNU C Library master sources branch master updated. glibc-2.25-525-gbeb52f5

[wilco at sourceware dot org]

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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=beb52f502f0477465313675d2a0fbf3962e130b8

commit beb52f502f0477465313675d2a0fbf3962e130b8
Author: Wilco Dijkstra <wdijkstr@arm.com>
Date:   Tue Jun 20 16:26:26 2017 +0100

    Improve math benchmark infrastructure
    
    Improve support for math function benchmarking.  This patch adds
    a feature that allows accurate benchmarking of traces extracted
    from real workloads.  This is done by iterating over all samples
    rather than repeating each sample many times (which completely
    ignores branch prediction and cache effects).  A trace can be
    added to existing math function inputs via
    "## name: workload-<name>", followed by the trace.
    
            * benchtests/README: Describe workload feature.
            * benchtests/bench-skeleton.c (main): Add support for
            benchmarking traces from workloads.

diff --git a/ChangeLog b/ChangeLog
index 2d81375..80bb1f8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2017-06-20  Wilco Dijkstra  <wdijkstr@arm.com>
+
+	* benchtests/README: Describe workload feature.
+	* benchtests/bench-skeleton.c (main): Add support for
+	benchmarking traces from workloads.
+
 2017-06-20  Zack Weinberg  <zackw@panix.com>
 
 	* string/string.h (__mempcpy_inline): Delete.
diff --git a/benchtests/README b/benchtests/README
index 2c5f381..b015acf 100644
--- a/benchtests/README
+++ b/benchtests/README
@@ -102,6 +102,12 @@ the same file by using the `name' directive that looks something like this:
 See the pow-inputs file for an example of what such a partitioned input file
 would look like.
 
+It is also possible to measure throughput of a (partial) trace extracted from
+a real workload.  In this case the whole trace is iterated over multiple times
+rather than repeating every input multiple times.  This can be done via:
+
+  ##name: workload-<name>
+
 Benchmark Sets:
 ==============
 
diff --git a/benchtests/bench-skeleton.c b/benchtests/bench-skeleton.c
index 09eb78d..3c6dad7 100644
--- a/benchtests/bench-skeleton.c
+++ b/benchtests/bench-skeleton.c
@@ -68,34 +68,50 @@ main (int argc, char **argv)
       clock_gettime (CLOCK_MONOTONIC_RAW, &runtime);
       runtime.tv_sec += DURATION;
 
+      bool is_bench = strncmp (VARIANT (v), "workload-", 9) == 0;
       double d_total_i = 0;
       timing_t total = 0, max = 0, min = 0x7fffffffffffffff;
       int64_t c = 0;
+      uint64_t cur;
       while (1)
 	{
-	  for (i = 0; i < NUM_SAMPLES (v); i++)
+	  if (is_bench)
 	    {
-	      uint64_t cur;
+	      /* Benchmark a real trace of calls - all samples are iterated
+		 over once before repeating.  This models actual use more
+		 accurately than repeating the same sample many times.  */
 	      TIMING_NOW (start);
 	      for (k = 0; k < iters; k++)
-		BENCH_FUNC (v, i);
+		for (i = 0; i < NUM_SAMPLES (v); i++)
+		  BENCH_FUNC (v, i);
 	      TIMING_NOW (end);
-
 	      TIMING_DIFF (cur, start, end);
+	      TIMING_ACCUM (total, cur);
+	      d_total_i += iters * NUM_SAMPLES (v);
+	    }
+	  else
+	    for (i = 0; i < NUM_SAMPLES (v); i++)
+	      {
+		TIMING_NOW (start);
+		for (k = 0; k < iters; k++)
+		  BENCH_FUNC (v, i);
+		TIMING_NOW (end);
 
-	      if (cur > max)
-		max = cur;
+		TIMING_DIFF (cur, start, end);
 
-	      if (cur < min)
-		min = cur;
+		if (cur > max)
+		  max = cur;
 
-	      TIMING_ACCUM (total, cur);
-	      /* Accumulate timings for the value.  In the end we will divide
-	         by the total iterations.  */
-	      RESULT_ACCUM (cur, v, i, c * iters, (c + 1) * iters);
+		if (cur < min)
+		  min = cur;
 
-	      d_total_i += iters;
-	    }
+		TIMING_ACCUM (total, cur);
+		/* Accumulate timings for the value.  In the end we will divide
+		   by the total iterations.  */
+		RESULT_ACCUM (cur, v, i, c * iters, (c + 1) * iters);
+
+		d_total_i += iters;
+	      }
 	  c++;
 	  struct timespec curtime;
 
@@ -117,11 +133,16 @@ main (int argc, char **argv)
 
       json_attr_double (&json_ctx, "duration", d_total_s);
       json_attr_double (&json_ctx, "iterations", d_total_i);
-      json_attr_double (&json_ctx, "max", max / d_iters);
-      json_attr_double (&json_ctx, "min", min / d_iters);
-      json_attr_double (&json_ctx, "mean", d_total_s / d_total_i);
+      if (is_bench)
+	json_attr_double (&json_ctx, "throughput", d_total_s / d_total_i);
+      else
+	{
+	  json_attr_double (&json_ctx, "max", max / d_iters);
+	  json_attr_double (&json_ctx, "min", min / d_iters);
+	  json_attr_double (&json_ctx, "mean", d_total_s / d_total_i);
+	}
 
-      if (detailed)
+      if (detailed && !is_bench)
 	{
 	  json_array_begin (&json_ctx, "timings");
 

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog                   |    6 ++++
 benchtests/README           |    6 ++++
 benchtests/bench-skeleton.c |   57 +++++++++++++++++++++++++++++-------------
 3 files changed, 51 insertions(+), 18 deletions(-)


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