From d4505b895f2aa577a6b974ab4bd0a1fd0db60ceb Mon Sep 17 00:00:00 2001 From: Wilco Dijkstra Date: Thu, 17 Aug 2017 16:27:20 +0100 Subject: [PATCH] Add math benchmark latency test This patch further improves math function benchmarking by adding a latency test in addition to throughput. This enables more accurate comparisons of the math functions. The latency test works by creating a dependency on the previous iteration: func_res = F (func_res * zero + input[i]). The multiply by zero avoids changing the input. It reports reciprocal throughput and latency in nanoseconds (depending on the timing header used) and max/min throughput in iterations per second: "workload-spec2006.wrf": { "reciprocal-throughput": 100, "latency": 200, "max-throughput": 1.0e+07, "min-throughput": 5.0e+06 } * benchtests/bench-skeleton.c (main): Add support for latency benchmarking. * benchtests/scripts/bench.py: Add support for latency benchmarking. --- ChangeLog | 6 ++++++ benchtests/bench-skeleton.c | 27 +++++++++++++++++++++++---- benchtests/scripts/bench.py | 20 ++++++++++++++------ 3 files changed, 43 insertions(+), 10 deletions(-) diff --git a/ChangeLog b/ChangeLog index f11f6e1..08207b1 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,9 @@ +2017-08-17 Wilco Dijkstra + + * benchtests/bench-skeleton.c (main): Add support for + latency benchmarking. + * benchtests/scripts/bench.py: Add support for latency benchmarking. + 2017-08-17 H.J. Lu * Makeconfig (+link-pie-before-libc): Add CRT-* hook to override diff --git a/benchtests/bench-skeleton.c b/benchtests/bench-skeleton.c index 3c6dad7..955b2e1 100644 --- a/benchtests/bench-skeleton.c +++ b/benchtests/bench-skeleton.c @@ -71,8 +71,10 @@ main (int argc, char **argv) bool is_bench = strncmp (VARIANT (v), "workload-", 9) == 0; double d_total_i = 0; timing_t total = 0, max = 0, min = 0x7fffffffffffffff; + timing_t throughput = 0, latency = 0; int64_t c = 0; uint64_t cur; + BENCH_VARS; while (1) { if (is_bench) @@ -86,7 +88,16 @@ main (int argc, char **argv) BENCH_FUNC (v, i); TIMING_NOW (end); TIMING_DIFF (cur, start, end); - TIMING_ACCUM (total, cur); + TIMING_ACCUM (throughput, cur); + + TIMING_NOW (start); + for (k = 0; k < iters; k++) + for (i = 0; i < NUM_SAMPLES (v); i++) + BENCH_FUNC_LAT (v, i); + TIMING_NOW (end); + TIMING_DIFF (cur, start, end); + TIMING_ACCUM (latency, cur); + d_total_i += iters * NUM_SAMPLES (v); } else @@ -131,12 +142,20 @@ main (int argc, char **argv) /* Begin variant. */ json_attr_object_begin (&json_ctx, VARIANT (v)); - json_attr_double (&json_ctx, "duration", d_total_s); - json_attr_double (&json_ctx, "iterations", d_total_i); if (is_bench) - json_attr_double (&json_ctx, "throughput", d_total_s / d_total_i); + { + json_attr_double (&json_ctx, "reciprocal-throughput", + throughput / d_total_i); + json_attr_double (&json_ctx, "latency", latency / d_total_i); + json_attr_double (&json_ctx, "max-throughput", + d_total_i / throughput * 1000000000.0); + json_attr_double (&json_ctx, "min-throughput", + d_total_i / latency * 1000000000.0); + } else { + 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); diff --git a/benchtests/scripts/bench.py b/benchtests/scripts/bench.py index 8c1c9ee..33dc7b9 100755 --- a/benchtests/scripts/bench.py +++ b/benchtests/scripts/bench.py @@ -45,7 +45,7 @@ DEFINES_TEMPLATE = ''' # variant is represented by the _VARIANT structure. The ARGS structure # represents a single set of arguments. STRUCT_TEMPLATE = ''' -#define CALL_BENCH_FUNC(v, i) %(func)s (%(func_args)s) +#define CALL_BENCH_FUNC(v, i, x) %(func)s (x %(func_args)s) struct args { @@ -84,7 +84,9 @@ EPILOGUE = ''' #define RESULT(__v, __i) (variants[(__v)].in[(__i)].timing) #define RESULT_ACCUM(r, v, i, old, new) \\ ((RESULT ((v), (i))) = (RESULT ((v), (i)) * (old) + (r)) / ((new) + 1)) -#define BENCH_FUNC(i, j) ({%(getret)s CALL_BENCH_FUNC (i, j);}) +#define BENCH_FUNC(i, j) ({%(getret)s CALL_BENCH_FUNC (i, j, );}) +#define BENCH_FUNC_LAT(i, j) ({%(getret)s CALL_BENCH_FUNC (i, j, %(latarg)s);}) +#define BENCH_VARS %(defvar)s #define FUNCNAME "%(func)s" #include "bench-skeleton.c"''' @@ -122,17 +124,23 @@ def gen_source(func, directives, all_vals): # If we have a return value from the function, make sure it is # assigned to prevent the compiler from optimizing out the # call. + getret = '' + latarg = '' + defvar = '' + if directives['ret']: print('static %s volatile ret;' % directives['ret']) - getret = 'ret = ' - else: - getret = '' + print('static %s zero __attribute__((used)) = 0;' % directives['ret']) + getret = 'ret = func_res = ' + # Note this may not work if argument and result type are incompatible. + latarg = 'func_res * zero +' + defvar = '%s func_res = 0;' % directives['ret'] # Test initialization. if directives['init']: print('#define BENCH_INIT %s' % directives['init']) - print(EPILOGUE % {'getret': getret, 'func': func}) + print(EPILOGUE % {'getret': getret, 'func': func, 'latarg': latarg, 'defvar': defvar }) def _print_arg_data(func, directives, all_vals): -- 2.7.4