Subject: Re: [PATCH net-next v2 1/2] selftests/ptr_ring: add benchmark application for ptr_ring

From: "Michael S. Tsirkin" <[email-masked]>
Date: Fri, 25 Jun 2021 02:37:38 -0400

On Fri, Jun 25, 2021 at 11:18:55AM +0800, Yunsheng Lin wrote:
> Currently ptr_ring selftest is embedded within the virtio
> selftest, which involves some specific virtio operation,
> such as notifying and kicking.
> 
> As ptr_ring has been used by various subsystems, it deserves
> it's owner's selftest in order to benchmark different usecase
> of ptr_ring, such as page pool and pfifo_fast qdisc.
> 
> So add a simple application to benchmark ptr_ring performance.
> Currently two test mode is supported:
> Mode 0: Both enqueuing and dequeuing is done in a single thread,
>         it is called simple test mode in the test app.
> Mode 1: Enqueuing and dequeuing is done in different thread
>         concurrently, also known as SPSC(single-producer/
>         single-consumer) test.
> 
> The multi-producer/single-consumer test for pfifo_fast case is
> not added yet, which can be added if using CAS atomic operation
> to enable lockless multi-producer is proved to be better than
> using r->producer_lock.
> 
> Only supported on x86 and arm64 for now.
> 
> Signed-off-by: Yunsheng Lin <[email-masked]>
> ---
>  MAINTAINERS                                      |   5 +
>  tools/testing/selftests/ptr_ring/Makefile        |   6 +
>  tools/testing/selftests/ptr_ring/ptr_ring_test.c | 249 +++++++++++++++++++++++
>  tools/testing/selftests/ptr_ring/ptr_ring_test.h | 150 ++++++++++++++
>  4 files changed, 410 insertions(+)
>  create mode 100644 tools/testing/selftests/ptr_ring/Makefile
>  create mode 100644 tools/testing/selftests/ptr_ring/ptr_ring_test.c
>  create mode 100644 tools/testing/selftests/ptr_ring/ptr_ring_test.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index cc375fd..1227022 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -14847,6 +14847,11 @@ F:	drivers/net/phy/dp83640*
>  F:	drivers/ptp/*
>  F:	include/linux/ptp_cl*
>  
> +PTR RING BENCHMARK
> +M:	Yunsheng Lin <[email-masked]>
> +L:	[email-masked]
> +F:	tools/testing/selftests/ptr_ring/
> +
>  PTRACE SUPPORT
>  M:	Oleg Nesterov <[email-masked]>
>  S:	Maintained
> diff --git a/tools/testing/selftests/ptr_ring/Makefile b/tools/testing/selftests/ptr_ring/Makefile
> new file mode 100644
> index 0000000..346dea9
> --- /dev/null
> +++ b/tools/testing/selftests/ptr_ring/Makefile
> @@ -0,0 +1,6 @@
> +# SPDX-License-Identifier: GPL-2.0
> +LDLIBS = -lpthread
> +
> +TEST_GEN_PROGS := ptr_ring_test
> +
> +include ../lib.mk
> diff --git a/tools/testing/selftests/ptr_ring/ptr_ring_test.c b/tools/testing/selftests/ptr_ring/ptr_ring_test.c
> new file mode 100644
> index 0000000..4f32d3d
> --- /dev/null
> +++ b/tools/testing/selftests/ptr_ring/ptr_ring_test.c
> @@ -0,0 +1,249 @@
> +// SPDX-License-Identifier: GPL-2.0-only

Can we keep this GPL-2.0-or-later same as ptr ring itself?
Encourages reuse ...

> +/*
> + * Copyright (C) 2021 HiSilicon Limited.
> + */
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <unistd.h>
> +#include <string.h>
> +#include <errno.h>
> +#include <sys/time.h>
> +#include <malloc.h>
> +#include <assert.h>
> +#include <stdbool.h>
> +#include <pthread.h>
> +
> +#include "ptr_ring_test.h"
> +#include "../../../../include/linux/ptr_ring.h"
> +
> +#define MIN_RING_SIZE	2
> +#define MAX_RING_SIZE	10000000
> +
> +static struct ptr_ring ring ____cacheline_aligned_in_smp;
> +
> +struct worker_info {
> +	pthread_t tid;
> +	int test_count;
> +	bool error;
> +	long duration_us;
> +};
> +
> +static void *produce_worker(void *arg)
> +{
> +	struct worker_info *info = arg;
> +	struct timeval start, end;
> +	unsigned long i = 0;
> +	long sec, us;
> +	int ret;
> +
> +	gettimeofday(&start, NULL);
> +
> +	while (++i <= info->test_count) {
> +		while (__ptr_ring_full(&ring))
> +			cpu_relax();
> +
> +		ret = __ptr_ring_produce(&ring, (void *)i);
> +		if (ret) {
> +			fprintf(stderr, "produce failed: %d\n", ret);
> +			info->error = true;
> +			return NULL;
> +		}
> +	}
> +
> +	gettimeofday(&end, NULL);
> +
> +	sec = (end.tv_sec - start.tv_sec);
> +	us = ((sec * 1000000) + end.tv_usec) - (start.tv_usec);
> +	info->duration_us = us;
> +	info->error = false;
> +
> +	return NULL;
> +}

perf does all of this and more. Let's not reinvent the wheel - just run
the test.

> +
> +static void *consume_worker(void *arg)
> +{
> +	struct worker_info *info = arg;
> +	struct timeval start, end;
> +	unsigned long i = 0;
> +	long sec, us;
> +	int *ptr;
> +
> +	gettimeofday(&start, NULL);
> +
> +	while (++i <= info->test_count) {
> +		while (__ptr_ring_empty(&ring))
> +			cpu_relax();
> +
> +		ptr = __ptr_ring_consume(&ring);
> +		if ((unsigned long)ptr != i) {
> +			fprintf(stderr, "consumer failed, ptr: %lu, i: %lu\n",
> +				(unsigned long)ptr, i);
> +			info->error = true;
> +			return NULL;
> +		}
> +	}
> +
> +	gettimeofday(&end, NULL);
> +
> +	if (!__ptr_ring_empty(&ring)) {
> +		fprintf(stderr, "ring should be empty, test failed\n");
> +		info->error = true;
> +		return NULL;
> +	}
> +
> +	sec = (end.tv_sec - start.tv_sec);
> +	us = ((sec * 1000000) + end.tv_usec) - (start.tv_usec);
> +	info->duration_us = us;
> +	info->error = false;
> +	return NULL;
> +}
> +
> +/* test case for single producer single consumer */
> +static void spsc_test(int size, int count)
> +{
> +	struct worker_info producer, consumer;
> +	pthread_attr_t attr;
> +	void *res;
> +	int ret;
> +
> +	ret = ptr_ring_init(&ring, size, 0);
> +	if (ret) {
> +		fprintf(stderr, "init failed: %d\n", ret);
> +		return;
> +	}
> +
> +	producer.test_count = count;
> +	consumer.test_count = count;
> +
> +	ret = pthread_attr_init(&attr);
> +	if (ret) {
> +		fprintf(stderr, "pthread attr init failed: %d\n", ret);
> +		goto out;
> +	}
> +
> +	ret = pthread_create(&producer.tid, &attr,
> +			     produce_worker, &producer);
> +	if (ret) {
> +		fprintf(stderr, "create producer thread failed: %d\n", ret);
> +		goto out;
> +	}
> +
> +	ret = pthread_create(&consumer.tid, &attr,
> +			     consume_worker, &consumer);
> +	if (ret) {
> +		fprintf(stderr, "create consumer thread failed: %d\n", ret);
> +		goto out;
> +	}
> +
> +	ret = pthread_join(producer.tid, &res);
> +	if (ret) {
> +		fprintf(stderr, "join producer thread failed: %d\n", ret);
> +		goto out;
> +	}
> +
> +	ret = pthread_join(consumer.tid, &res);
> +	if (ret) {
> +		fprintf(stderr, "join consumer thread failed: %d\n", ret);
> +		goto out;
> +	}
> +
> +	if (producer.error || consumer.error) {
> +		fprintf(stderr, "spsc test failed\n");
> +		goto out;
> +	}
> +
> +	printf("ptr_ring(size:%d) perf spsc test for %d times, took %ld us + %ld us\n",
> +	       size, count, producer.duration_us, consumer.duration_us);
> +out:
> +	ptr_ring_cleanup(&ring, NULL);
> +}
> +
> +static void simple_test(int size, int count)
> +{
> +	struct timeval start, end;
> +	long sec, us;
> +	int i = 0;
> +	int *ptr;
> +	int ret;
> +
> +	ret = ptr_ring_init(&ring, size, 0);
> +	if (ret) {
> +		fprintf(stderr, "init failed: %d\n", ret);
> +		return;
> +	}
> +
> +	gettimeofday(&start, NULL);
> +
> +	while (++i <= count) {
> +		ret = __ptr_ring_produce(&ring, &count);
> +		if (ret) {
> +			fprintf(stderr, "produce failed: %d\n", ret);
> +			goto out;
> +		}
> +
> +		ptr = __ptr_ring_consume(&ring);
> +		if (ptr != &count)  {
> +			fprintf(stderr, "consume failed: %p\n", ptr);
> +			goto out;
> +		}
> +	}
> +
> +	gettimeofday(&end, NULL);
> +	sec = (end.tv_sec - start.tv_sec);
> +	us = ((sec * 1000000) + end.tv_usec) - (start.tv_usec);
> +	printf("ptr_ring(size:%d) perf simple test for %d times, took %ld us\n",
> +	       size, count, us);
> +
> +out:
> +	ptr_ring_cleanup(&ring, NULL);
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	int count = 1000000;
> +	int size = 1000;
> +	int mode = 0;
> +	int opt;
> +
> +	while ((opt = getopt(argc, argv, "N:s:m:")) != -1) {
> +		switch (opt) {
> +		case 'N':
> +			count = atoi(optarg);
> +			break;
> +		case 's':
> +			size = atoi(optarg);
> +			break;
> +		case 'm':
> +			mode = atoi(optarg);
> +			break;
> +		default:
> +			return -1;
> +		}
> +	}
> +
> +	if (count <= 0) {
> +		fprintf(stderr, "invalid test count, must be > 0\n");
> +		return -1;
> +	}
> +
> +	if (size < MIN_RING_SIZE || size > MAX_RING_SIZE) {
> +		fprintf(stderr, "invalid ring size, must be in %d-%d\n",
> +			MIN_RING_SIZE, MAX_RING_SIZE);
> +		return -1;
> +	}
> +
> +	switch (mode) {
> +	case 0:
> +		simple_test(size, count);
> +		break;
> +	case 1:
> +		spsc_test(size, count);
> +		break;
> +	default:
> +		fprintf(stderr, "invalid test mode\n");
> +		return -1;
> +	}
> +
> +	return 0;
> +}
> diff --git a/tools/testing/selftests/ptr_ring/ptr_ring_test.h b/tools/testing/selftests/ptr_ring/ptr_ring_test.h
> new file mode 100644
> index 0000000..6bf2494
> --- /dev/null
> +++ b/tools/testing/selftests/ptr_ring/ptr_ring_test.h
> @@ -0,0 +1,150 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */

We already have hacks like this in the virtio test.
Let's refactor not duplicate please.

> +
> +#ifndef _TEST_PTR_RING_IMPL_H
> +#define _TEST_PTR_RING_IMPL_H
> +
> +#if defined(__x86_64__) || defined(__i386__)
> +static inline void cpu_relax(void)
> +{
> +	asm volatile ("rep; nop" ::: "memory");
> +}
> +#elif defined(__aarch64__)
> +static inline void cpu_relax(void)
> +{
> +	asm volatile("yield" ::: "memory");
> +}
> +#else
> +#define cpu_relax() assert(0)
> +#endif
> +
> +static inline void barrier(void)
> +{
> +	asm volatile("" ::: "memory");
> +}
> +
> +/*
> + * This abuses the atomic builtins for thread fences, and
> + * adds a compiler barrier.
> + */
> +#define smp_release() do { \
> +	barrier(); \
> +	__atomic_thread_fence(__ATOMIC_RELEASE); \
> +} while (0)
> +
> +#define smp_acquire() do { \
> +	__atomic_thread_fence(__ATOMIC_ACQUIRE); \
> +	barrier(); \
> +} while (0)
> +
> +#if defined(__i386__) || defined(__x86_64__)
> +#define smp_wmb()		barrier()
> +#else
> +#define smp_wmb()		smp_release()
> +#endif
> +
> +#define READ_ONCE(x)		(*(volatile typeof(x) *)&(x))
> +#define WRITE_ONCE(x, val)	((*(volatile typeof(x) *)&(x)) = (val))
> +#define SMP_CACHE_BYTES		64
> +#define cache_line_size		SMP_CACHE_BYTES
> +#define unlikely(x)		(__builtin_expect(!!(x), 0))
> +#define likely(x)		(__builtin_expect(!!(x), 1))
> +#define ALIGN(x, a)		(((x) + (a) - 1) / (a) * (a))
> +#define SIZE_MAX		(~(size_t)0)
> +#define KMALLOC_MAX_SIZE	SIZE_MAX
> +#define spinlock_t		pthread_spinlock_t
> +#define gfp_t			int
> +#define __GFP_ZERO		0x1
> +
> +#define ____cacheline_aligned_in_smp __attribute__((aligned(SMP_CACHE_BYTES)))
> +
> +static void *kmalloc(unsigned int size, gfp_t gfp)
> +{
> +	void *p;
> +
> +	p = memalign(64, size);
> +	if (!p)
> +		return p;
> +
> +	if (gfp & __GFP_ZERO)
> +		memset(p, 0, size);
> +
> +	return p;
> +}
> +
> +static inline void *kzalloc(unsigned int size, gfp_t flags)
> +{
> +	return kmalloc(size, flags | __GFP_ZERO);
> +}
> +
> +static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
> +{
> +	if (size != 0 && n > SIZE_MAX / size)
> +		return NULL;
> +	return kmalloc(n * size, flags);
> +}
> +
> +static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
> +{
> +	return kmalloc_array(n, size, flags | __GFP_ZERO);
> +}
> +
> +static void kfree(void *p)
> +{
> +	free(p);
> +}
> +
> +#define kvmalloc_array		kmalloc_array
> +#define kvfree			kfree
> +
> +static void spin_lock_init(spinlock_t *lock)
> +{
> +	int r = pthread_spin_init(lock, 0);
> +
> +	assert(!r);
> +}
> +
> +static void spin_lock(spinlock_t *lock)
> +{
> +	int ret = pthread_spin_lock(lock);
> +
> +	assert(!ret);
> +}
> +
> +static void spin_unlock(spinlock_t *lock)
> +{
> +	int ret = pthread_spin_unlock(lock);
> +
> +	assert(!ret);
> +}
> +
> +static void spin_lock_bh(spinlock_t *lock)
> +{
> +	spin_lock(lock);
> +}
> +
> +static void spin_unlock_bh(spinlock_t *lock)
> +{
> +	spin_unlock(lock);
> +}
> +
> +static void spin_lock_irq(spinlock_t *lock)
> +{
> +	spin_lock(lock);
> +}
> +
> +static void spin_unlock_irq(spinlock_t *lock)
> +{
> +	spin_unlock(lock);
> +}
> +
> +static void spin_lock_irqsave(spinlock_t *lock, unsigned long f)
> +{
> +	spin_lock(lock);
> +}
> +
> +static void spin_unlock_irqrestore(spinlock_t *lock, unsigned long f)
> +{
> +	spin_unlock(lock);
> +}
> +
> +#endif
> -- 
> 2.7.4