From patchwork Thu Jul 16 11:15:19 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wilco Dijkstra X-Patchwork-Id: 7716 Received: (qmail 50770 invoked by alias); 16 Jul 2015 11:15:34 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 50754 invoked by uid 89); 16 Jul 2015 11:15:33 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.8 required=5.0 tests=AWL, BAYES_00, SPF_PASS autolearn=ham version=3.3.2 X-HELO: eu-smtp-delivery-143.mimecast.com From: "Wilco Dijkstra" To: "'GNU C Library'" Subject: [PATCH v2] Add math-inline benchmark Date: Thu, 16 Jul 2015 12:15:19 +0100 Message-ID: <002001d0bfb8$b36fa330$1a4ee990$@com> MIME-Version: 1.0 X-MC-Unique: zBaT_FTLQ3C5UXtUOTzdxg-1 Add a benchmark for isinf/isnan/isnormal/isfinite/fpclassify. This new version adds explicit tests for the GCC built-ins and uses json format as suggested and no longer includes any string headers. The test uses 2 arrays with 1024 doubles, one with 99% finite FP numbers (10% zeroes, 10% negative) and 1% inf/NaN, the other with 50% inf, and 50% Nan. Results shows that using the GCC built-ins in math.h gives huge speedups due to avoiding explict calls, PLT indirection to execute a function with 3-4 instructions - around 7x on AArch64 and 2.8x on x64. The GCC builtins have better performance than the existing math_private inlines for __isnan, __finite and __isinf_ns, so these should be removed. ChangeLog: 2015-07-16 Wilco Dijkstra * benchtests/Makefile: Add bench-math-inlines, link with libm. * benchtests/bench-math-inlines.c: New benchmark. --- benchtests/Makefile | 7 +- benchtests/bench-math-inlines.c | 353 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 359 insertions(+), 1 deletion(-) create mode 100644 benchtests/bench-math-inlines.c diff --git a/benchtests/Makefile b/benchtests/Makefile index 8e615e5..91970f8 100644 --- a/benchtests/Makefile +++ b/benchtests/Makefile @@ -36,6 +36,7 @@ string-bench := bcopy bzero memccpy memchr memcmp memcpy memmem memmove \ strncasecmp strncat strncmp strncpy strnlen strpbrk strrchr \ strspn strstr strcpy_chk stpcpy_chk memrchr strsep strtok \ strcoll + string-bench-all := $(string-bench) # We have to generate locales @@ -50,7 +51,10 @@ stdlib-bench := strtod stdio-common-bench := sprintf -benchset := $(string-bench-all) $(stdlib-bench) $(stdio-common-bench) +math-benchset := math-inlines + +benchset := $(string-bench-all) $(stdlib-bench) $(stdio-common-bench) \ + $(math-benchset) CFLAGS-bench-ffs.c += -fno-builtin CFLAGS-bench-ffsll.c += -fno-builtin @@ -58,6 +62,7 @@ CFLAGS-bench-ffsll.c += -fno-builtin bench-malloc := malloc-thread $(addprefix $(objpfx)bench-,$(bench-math)): $(libm) +$(addprefix $(objpfx)bench-,$(math-benchset)): $(libm) $(addprefix $(objpfx)bench-,$(bench-pthread)): $(shared-thread-library) $(objpfx)bench-malloc-thread: $(shared-thread-library) diff --git a/benchtests/bench-math-inlines.c b/benchtests/bench-math-inlines.c new file mode 100644 index 0000000..fac3f1a --- /dev/null +++ b/benchtests/bench-math-inlines.c @@ -0,0 +1,353 @@ +/* Measure math inline functions. + Copyright (C) 2015 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#define SIZE 1024 +#define TEST_MAIN +#define TEST_NAME "math-inlines" +#define TEST_FUNCTION test_main () +#include "bench-timing.h" +#include "json-lib.h" + +#include +#include +#include + + +#define BOOLTEST(func) \ +int \ +func ## _t (volatile double *p, size_t n, size_t iters) \ +{ \ + int i, j; \ + int res = 0; \ + for (j = 0; j < iters; j++) \ + for (i = 0; i < n; i++) \ + { double tmp = p[i] * 2.0; \ + if (func (tmp)) res += 5; } \ + return res; \ +} + +#define VALUETEST(func) \ +int \ +func ## _t (volatile double *p, size_t n, size_t iters) \ +{ \ + int i, j; \ + int res = 0; \ + for (j = 0; j < iters; j++) \ + for (i = 0; i < n; i++) \ + { double tmp = p[i] * 2.0; \ + if (func (tmp)) res += 5; } \ + return res; \ +} + +typedef union +{ + double value; + uint64_t word; +} ieee_double_shape_type; + +#define EXTRACT_WORDS64(i,d) \ +do { \ + ieee_double_shape_type gh_u; \ + gh_u.value = (d); \ + (i) = gh_u.word; \ +} while (0) + +/* Explicit inlines similar to math_private.h versions. */ + +extern __always_inline int +__isnan_inl (double d) +{ + uint64_t di; + EXTRACT_WORDS64 (di, d); + return (di & 0x7fffffffffffffffull) > 0x7ff0000000000000ull; +} + +extern __always_inline int +__isnan_builtin (double d) +{ + return __builtin_isnan (d); +} + +extern __always_inline int +__isinf_inl (double x) +{ + uint64_t ix; + EXTRACT_WORDS64 (ix,x); + if ((ix << 1) != 0xffe0000000000000ull) + return 0; + return (int)(ix >> 32); +} + +extern __always_inline int +__isinf_ns (double d) +{ + uint64_t di; + EXTRACT_WORDS64 (di, d); + return (di & 0x7fffffffffffffffull) == 0x7ff0000000000000ull; +} + +extern __always_inline int +__isinf_ns_builtin (double d) +{ + return __builtin_isinf (d); +} + +extern __always_inline int +__isinf_builtin (double d) +{ + return __builtin_isinf_sign (d); +} + + +extern __always_inline int +__finite_inl (double d) +{ + uint64_t di; + EXTRACT_WORDS64 (di, d); + return (di & 0x7fffffffffffffffull) < 0x7ff0000000000000ull; +} + +extern __always_inline int +__isfinite_builtin (double d) +{ + return __builtin_isfinite (d); +} + + +/* Explicit inline similar to existing math.h implementation. */ + +#define __isnormal_inl(X) (__fpclassify (X) == FP_NORMAL) +#define __isnormal_inl2(X) (fpclassify (X) == FP_NORMAL) + +extern __always_inline int +__isnormal_builtin (double d) +{ + return __builtin_isnormal (d); +} + +/* Test fpclassify with use of only 2 of the 5 results. */ + +extern __always_inline int +__fpclassify_test1 (double d) +{ + int cl = fpclassify (d); + return cl == FP_NAN || cl == FP_INFINITE; +} + +extern __always_inline int +__fpclassify_test2 (double d) +{ + return __builtin_isnan (d) || __builtin_isinf (d); +} + +double __attribute ((noinline)) +kernel_standard (double x, double y, int z) +{ + return x * y + z; +} + +double __attribute ((noinline)) +remainder2 (double x, double y) +{ + if (((__builtin_expect (y == 0.0, 0) && !__builtin_isnan (x)) + || (__builtin_expect (__builtin_isinf (x), 0) && !__builtin_isnan (y)))) + return kernel_standard (x, y, 10); + + return remainder (x, y); +} + +double __attribute ((noinline)) +remainder1 (double x, double y) +{ + if (((__builtin_expect (y == 0.0, 0) && !__isnan_inl (x)) + || (__builtin_expect (__isinf_ns (x), 0) && !__isnan_inl (y)))) + return kernel_standard (x, y, 10); + + return remainder (x, y); +} + +volatile double rem1 = 2.5; + +extern __always_inline int +remainder_test1 (double d) +{ + return remainder1 (d, rem1); +} + +extern __always_inline int +remainder_test2 (double d) +{ + return remainder2 (d, rem1); +} + +/* Create test functions for each possibility. */ + +BOOLTEST (__isnan) +BOOLTEST (__isnan_inl) +BOOLTEST (__isnan_builtin) +BOOLTEST (isnan) + +BOOLTEST (__isinf) +BOOLTEST (__isinf_inl) +BOOLTEST (__isinf_ns) +BOOLTEST (__isinf_ns_builtin) +BOOLTEST (__isinf_builtin) +BOOLTEST (isinf) + +BOOLTEST (__finite) +BOOLTEST (__finite_inl) +BOOLTEST (__isfinite_builtin) +BOOLTEST (isfinite) + +BOOLTEST (__isnormal_inl) +BOOLTEST (__isnormal_inl2) +BOOLTEST (__isnormal_builtin) +BOOLTEST (isnormal) + +BOOLTEST (__fpclassify_test1) +BOOLTEST (__fpclassify_test2) +VALUETEST (__fpclassify) +VALUETEST (fpclassify) + +BOOLTEST (remainder_test1) +BOOLTEST (remainder_test2) + +typedef int (*proto_t) (volatile double *p, size_t n, size_t iters); + +typedef struct +{ + const char *name; + proto_t fn; +} impl_t; + +#define IMPL(name) { #name, name } + +impl_t test_list[] = +{ + IMPL (__isnan_t), + IMPL (__isnan_inl_t), + IMPL (__isnan_builtin_t), + IMPL (isnan_t), + + IMPL (__isinf_t), + IMPL (__isinf_inl_t), + IMPL (__isinf_ns_t), + IMPL (__isinf_ns_builtin_t), + IMPL (__isinf_builtin_t), + IMPL (isinf_t), + + IMPL (__finite_t), + IMPL (__finite_inl_t), + IMPL (__isfinite_builtin_t), + IMPL (isfinite_t), + + IMPL (__isnormal_inl_t), + IMPL (__isnormal_inl2_t), + IMPL (__isnormal_builtin_t), + IMPL (isnormal_t), + + IMPL (__fpclassify_test1_t), + IMPL (__fpclassify_test2_t), + IMPL (__fpclassify_t), + IMPL (fpclassify_t), + + IMPL (remainder_test1_t), + IMPL (remainder_test2_t) +}; + +static void +do_one_test (json_ctx_t *json_ctx, proto_t test_fn, volatile double *arr, + size_t len, const char *testname) +{ + size_t iters = 500; + timing_t start, stop, cur; + + json_attr_object_begin (json_ctx, testname); + + TIMING_NOW (start); + test_fn (arr, len, iters); + TIMING_NOW (stop); + TIMING_DIFF (cur, start, stop); + + json_attr_double (json_ctx, "duration", cur); + json_attr_double (json_ctx, "iterations", iters); + json_attr_double (json_ctx, "mean", cur / iters); + json_attr_object_end (json_ctx); +} + +volatile unsigned int dontoptimize = 0; + +void +startup (void) +{ + /* This loop should cause CPU to switch to maximal freqency. + This makes subsequent measurement more accurate. We need a side effect + to prevent the loop being deleted by compiler. + This should be enough to cause CPU to speed up and it is simpler than + running loop for constant time. This is used when user does not have root + access to set a constant freqency. */ + for (int k = 0; k < 100000000; k++) + dontoptimize += 23 * dontoptimize + 2; +} + +static volatile double arr1[SIZE]; +static volatile double arr2[SIZE]; + +int +test_main (void) +{ + json_ctx_t json_ctx; + size_t i; + + startup (); + + json_init (&json_ctx, 2, stdout); + json_attr_object_begin (&json_ctx, "math-inlines"); + + /* Create 2 test arrays, one with 10% zeroes, 10% negative values, + 79% positive values and 1% infinity/NaN. The other contains + 50% inf, 50% NaN. */ + + for (i = 0; i < SIZE; i++) + { + int x = rand () & 255; + arr1[i] = (x < 25) ? 0.0 : ((x < 50) ? -1 : 100); + if (x == 255) arr1[i] = __builtin_inf (); + if (x == 254) arr1[i] = __builtin_nan ("0"); + arr2[i] = (x < 128) ? __builtin_inf () : __builtin_nan ("0"); + } + + for (i = 0; i < sizeof (test_list) / sizeof (test_list[0]); i++) + { + json_attr_object_begin (&json_ctx, test_list[i].name); + do_one_test (&json_ctx, test_list[i].fn, arr2, SIZE, "inf/nan"); + json_attr_object_end (&json_ctx); + } + + for (i = 0; i < sizeof (test_list) / sizeof (test_list[0]); i++) + { + json_attr_object_begin (&json_ctx, test_list[i].name); + do_one_test (&json_ctx, test_list[i].fn, arr1, SIZE, "normal"); + json_attr_object_end (&json_ctx); + } + + json_attr_object_end (&json_ctx); + return 0; +} + +#include "../test-skeleton.c"