[PATCH 3/7] benchtests: Add arc4random benchtest
Noah Goldstein
goldstein.w.n@gmail.com
Thu Apr 14 19:17:39 GMT 2022
On Wed, Apr 13, 2022 at 3:26 PM Adhemerval Zanella via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> It shows both throughput (total bytes obtained in the test duration)
> and latecy for both arc4random and arc4random_buf with different
> sizes.
>
> Checked on x86_64-linux-gnu, aarch64-linux, and powerpc64le-linux-gnu.
> ---
> benchtests/Makefile | 6 +-
> benchtests/bench-arc4random.c | 243 ++++++++++++++++++++++++++++++++++
> 2 files changed, 248 insertions(+), 1 deletion(-)
> create mode 100644 benchtests/bench-arc4random.c
>
> diff --git a/benchtests/Makefile b/benchtests/Makefile
> index 8dfca592fd..50b96dd71f 100644
> --- a/benchtests/Makefile
> +++ b/benchtests/Makefile
> @@ -111,8 +111,12 @@ bench-string := \
> ffsll \
> # bench-string
>
> +bench-stdlib := \
> + arc4random \
> +# bench-stdlib
> +
> ifeq (${BENCHSET},)
> -bench := $(bench-math) $(bench-pthread) $(bench-string)
> +bench := $(bench-math) $(bench-pthread) $(bench-string) $(bench-stdlib)
> else
> bench := $(foreach B,$(filter bench-%,${BENCHSET}), ${${B}})
> endif
> diff --git a/benchtests/bench-arc4random.c b/benchtests/bench-arc4random.c
> new file mode 100644
> index 0000000000..9e2ba9ba34
> --- /dev/null
> +++ b/benchtests/bench-arc4random.c
> @@ -0,0 +1,243 @@
> +/* arc4random benchmarks.
> + Copyright (C) 2022 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
> + <https://www.gnu.org/licenses/>. */
> +
> +#include "bench-timing.h"
> +#include "json-lib.h"
> +#include <array_length.h>
> +#include <intprops.h>
> +#include <signal.h>
> +#include <stdbool.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/support.h>
> +#include <support/xthread.h>
> +
> +static volatile uint32_t r;
> +static volatile sig_atomic_t timer_finished;
> +
> +static void timer_callback (int unused)
> +{
> + timer_finished = 1;
> +}
> +
> +static const uint32_t sizes[] = { 0, 16, 32, 64, 128 };
> +
> +static double
> +bench_arc4random_throughput (void)
> +{
> + /* Run for approximately DURATION seconds, and it does not matter who
> + receive the signal (so not need to mask it on main thread). */
> + timer_finished = 0;
> + timer_t timer = support_create_timer (DURATION, 0, false, timer_callback);
> +
> + uint64_t n = 0;
> +
> + while (1)
> + {
> + r = arc4random ();
> + n++;
> +
> + if (timer_finished == 1)
> + break;
> + }
> +
> + support_delete_timer (timer);
> +
> + return (double) (n * sizeof (r)) / (double) DURATION;
> +}
> +
> +static double
> +bench_arc4random_latency (void)
> +{
> + timing_t start, stop, cur;
> + const size_t iters = 1024;
> +
> + TIMING_NOW (start);
> + for (size_t i = 0; i < iters; i++)
> + r = arc4random ();
> + TIMING_NOW (stop);
> +
> + TIMING_DIFF (cur, start, stop);
> +
> + return (double) (cur) / (double) iters;
> +}
> +
> +static double
> +bench_arc4random_buf_throughput (size_t len)
> +{
> + timer_finished = 0;
> + timer_t timer = support_create_timer (DURATION, 0, false, timer_callback);
> +
> + uint8_t buf[len];
> +
> + uint64_t n = 0;
> +
> + while (1)
> + {
> + arc4random_buf (buf, len);
> + n++;
> +
> + if (timer_finished == 1)
> + break;
> + }
> +
> + support_delete_timer (timer);
> +
> + uint64_t total = (n * len);
> + return (double) (total) / (double) DURATION;
> +}
> +
> +static double
> +bench_arc4random_buf_latency (size_t len)
> +{
> + timing_t start, stop, cur;
> + const size_t iters = 1024;
> +
> + uint8_t buf[len];
> +
> + TIMING_NOW (start);
> + for (size_t i = 0; i < iters; i++)
> + arc4random_buf (buf, len);
> + TIMING_NOW (stop);
> +
> + TIMING_DIFF (cur, start, stop);
> +
> + return (double) (cur) / (double) iters;
> +}
> +
> +static void
> +bench_singlethread (json_ctx_t *json_ctx)
> +{
> + json_element_object_begin (json_ctx);
> +
> + json_array_begin (json_ctx, "throughput");
> + for (int i = 0; i < array_length (sizes); i++)
> + if (sizes[i] == 0)
> + json_element_double (json_ctx, bench_arc4random_throughput ());
> + else
> + json_element_double (json_ctx, bench_arc4random_buf_throughput (sizes[i]));
> + json_array_end (json_ctx);
> +
> + json_array_begin (json_ctx, "latency");
> + for (int i = 0; i < array_length (sizes); i++)
> + if (sizes[i] == 0)
> + json_element_double (json_ctx, bench_arc4random_latency ());
> + else
> + json_element_double (json_ctx, bench_arc4random_buf_latency (sizes[i]));
> + json_array_end (json_ctx);
> +
> + json_element_object_end (json_ctx);
> +}
> +
> +struct thr_arc4random_arg
> +{
> + double ret;
> + uint32_t val;
> +};
> +
> +static void *
> +thr_arc4random_throughput (void *closure)
> +{
> + struct thr_arc4random_arg *arg = closure;
> + arg->ret = arg->val == 0 ? bench_arc4random_throughput ()
> + : bench_arc4random_buf_throughput (arg->val);
> + return NULL;
> +}
> +
> +static void *
> +thr_arc4random_latency (void *closure)
> +{
> + struct thr_arc4random_arg *arg = closure;
> + arg->ret = arg->val == 0 ? bench_arc4random_latency ()
> + : bench_arc4random_buf_latency (arg->val);
> + return NULL;
> +}
I think the expectation is that the chacha calls will be cold,
maybe it is worth adding a cache flush of sorts between
calls. It may be some prefetching in the start will help the code in
that case but would only be a regression with the hot in L1
benchmarks.
Can wait though this V1 looks fine.
> +
> +static void
> +bench_threaded (json_ctx_t *json_ctx)
> +{
> + json_element_object_begin (json_ctx);
> +
> + json_array_begin (json_ctx, "throughput");
> + for (int i = 0; i < array_length (sizes); i++)
> + {
> + struct thr_arc4random_arg arg = { .val = sizes[i] };
> + pthread_t thr = xpthread_create (NULL, thr_arc4random_throughput, &arg);
> + xpthread_join (thr);
> + json_element_double (json_ctx, arg.ret);
> + }
> + json_array_end (json_ctx);
> +
> + json_array_begin (json_ctx, "latency");
> + for (int i = 0; i < array_length (sizes); i++)
> + {
> + struct thr_arc4random_arg arg = { .val = sizes[i] };
> + pthread_t thr = xpthread_create (NULL, thr_arc4random_latency, &arg);
> + xpthread_join (thr);
> + json_element_double (json_ctx, arg.ret);
> + }
> + json_array_end (json_ctx);
> +
> + json_element_object_end (json_ctx);
> +}
> +
> +static void
> +run_bench (json_ctx_t *json_ctx, const char *name,
> + char *const*fnames, size_t fnameslen,
> + void (*bench)(json_ctx_t *ctx))
> +{
> + json_attr_object_begin (json_ctx, name);
> + json_array_begin (json_ctx, "functions");
> + for (int i = 0; i < fnameslen; i++)
> + json_element_string (json_ctx, fnames[i]);
> + json_array_end (json_ctx);
> +
> + json_array_begin (json_ctx, "results");
> + bench (json_ctx);
> + json_array_end (json_ctx);
> + json_attr_object_end (json_ctx);
> +}
> +
> +static int
> +do_test (void)
> +{
> + char *fnames[array_length (sizes) + 1];
> + fnames[0] = (char *) "arc4random";
> + for (int i = 0; i < array_length (sizes); i++)
> + fnames[i+1] = xasprintf ("arc4random_buf(%u)", sizes[i]);
> +
> + json_ctx_t json_ctx;
> + json_init (&json_ctx, 0, stdout);
> +
> + json_document_begin (&json_ctx);
> + json_attr_string (&json_ctx, "timing_type", TIMING_TYPE);
> +
> + run_bench (&json_ctx, "single-thread", fnames, array_length (fnames),
> + bench_singlethread);
> + run_bench (&json_ctx, "multi-thread", fnames, array_length (fnames),
> + bench_threaded);
> +
> + json_document_end (&json_ctx);
> +
> + for (int i = 0; i < array_length (sizes); i++)
> + free (fnames[i+1]);
> +
> + return 0;
> +}
> +
> +#include <support/test-driver.c>
> --
> 2.32.0
>
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