在 2021/7/1 下午8:26, Yunsheng Lin 写道:

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 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 producing and consuming is done in a single thread, it is called simple test mode in the test app. Mode 1: Producing and consuming 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.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com> --- V3: Remove timestamp sampling, use standard C library as much as possible. --- MAINTAINERS | 5 + tools/testing/selftests/ptr_ring/Makefile | 6 + tools/testing/selftests/ptr_ring/ptr_ring_test.c | 224 +++++++++++++++++++++++ tools/testing/selftests/ptr_ring/ptr_ring_test.h | 130 +++++++++++++ 4 files changed, 365 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 <linyunsheng@huawei.com> +L: netdev@vger.kernel.org +F: tools/testing/selftests/ptr_ring/ + PTRACE SUPPORT M: Oleg Nesterov <oleg@redhat.com> 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..4a5312f --- /dev/null +++ b/tools/testing/selftests/ptr_ring/ptr_ring_test.c @@ -0,0 +1,224 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2021 HiSilicon Limited. + */ + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <string.h> +#include <errno.h> +#include <malloc.h> +#include <stdbool.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; +}; + +static void *produce_worker(void *arg) +{ + struct worker_info *info = arg; + unsigned long i = 0; + int ret; + + 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; + } + } + + info->error = false; + + return NULL; +} + +static void *consume_worker(void *arg) +{ + struct worker_info *info = arg; + unsigned long i = 0; + int *ptr; + + while (++i <= info->test_count) { + while (__ptr_ring_empty(&ring)) + cpu_relax();

Any reason for not simply use __ptr_ring_consume() here?

+ + 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; + } + } + + if (!__ptr_ring_empty(&ring)) { + fprintf(stderr, "ring should be empty, test failed\n"); + info->error = true; + return NULL; + } + + 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 produced/comsumed %d items, finished\n", + size, count); +out: + ptr_ring_cleanup(&ring, NULL); +} + +static void simple_test(int size, int count) +{ + struct timeval start, end; + int i = 0; + int *ptr; + int ret; + + ret = ptr_ring_init(&ring, size, 0); + if (ret) { + fprintf(stderr, "init failed: %d\n", ret); + return; + } + + 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; + } + } + + printf("ptr_ring(size:%d) perf simple test produced/consumed %d items, finished\n", + size, count); + +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:h")) != -1) { + switch (opt) { + case 'N': + count = atoi(optarg); + break; + case 's': + size = atoi(optarg); + break; + case 'm': + mode = atoi(optarg); + break; + case 'h': + printf("usage: ptr_ring_test [-N COUNT] [-s RING_SIZE] [-m TEST_MODE]\n"); + return 0; + 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..32bfefb --- /dev/null +++ b/tools/testing/selftests/ptr_ring/ptr_ring_test.h

Let's reuse ptr_ring.c in tools/virtio/ringtest. Nothing virt specific there. Thanks

@@ -0,0 +1,130 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +#ifndef _TEST_PTR_RING_TEST_H +#define _TEST_PTR_RING_TEST_H + +#include <assert.h> +#include <stdatomic.h> +#include <pthread.h> + +/* Assuming the cache line size is 64 for most cpu, + * change it accordingly if the running cpu has different + * cache line size in order to get more accurate result. + */ +#define SMP_CACHE_BYTES 64 + +#define cpu_relax() sched_yield() +#define smp_release() atomic_thread_fence(memory_order_release) +#define smp_acquire() atomic_thread_fence(memory_order_acquire) +#define smp_wmb() smp_release() +#define smp_store_release(p, v) \ + atomic_store_explicit(p, v, memory_order_release) + +#define READ_ONCE(x) (*(volatile typeof(x) *)&(x)) +#define WRITE_ONCE(x, val) ((*(volatile typeof(x) *)&(x)) = (val)) +#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 inline 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 inline void kfree(void *p) +{ + free(p); +} + +#define kvmalloc_array kmalloc_array +#define kvfree kfree + +static inline void spin_lock_init(spinlock_t *lock) +{ + int r = pthread_spin_init(lock, 0); + + assert(!r); +} + +static inline void spin_lock(spinlock_t *lock) +{ + int ret = pthread_spin_lock(lock); + + assert(!ret); +} + +static inline void spin_unlock(spinlock_t *lock) +{ + int ret = pthread_spin_unlock(lock); + + assert(!ret); +} + +static inline void spin_lock_bh(spinlock_t *lock) +{ + spin_lock(lock); +} + +static inline void spin_unlock_bh(spinlock_t *lock) +{ + spin_unlock(lock); +} + +static inline void spin_lock_irq(spinlock_t *lock) +{ + spin_lock(lock); +} + +static inline void spin_unlock_irq(spinlock_t *lock) +{ + spin_unlock(lock); +} + +static inline void spin_lock_irqsave(spinlock_t *lock, + unsigned long f) +{ + spin_lock(lock); +} + +static inline void spin_unlock_irqrestore(spinlock_t *lock, + unsigned long f) +{ + spin_unlock(lock); +} + +#endif

在 2021/7/1 下午8:26, Yunsheng Lin 写道:

Currently r->queue[] clearing is done before r->consumer_head updating, which makes the __ptr_ring_empty() returning false positive result(the ring is non-empty, but __ptr_ring_empty() suggest that it is empty) if the checking is done after the r->queue clearing and before the consumer_head moving forward.

Move the r->queue[] clearing after consumer_head moving forward to avoid the above case.

As a side effect of above change, a consumer_head checking is avoided for the likely case, and it has noticeable performance improvement when it is tested using the ptr_ring_test selftest added in the previous patch.

Tested using the "perf stat -r 1000 ./ptr_ring_test -s 1000 -m 1 -N 100000000", comparing the elapsed time:

arch unpatched patched improvement arm64 2.087205 sec 1.888224 sec +9.5% X86 2.6538 sec 2.5422 sec +4.2%

I think we need the number of real workloads here. Thanks

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com> --- V3: adjust the title and comment log according to disscusion in V2, and update performance data using "perf stat -r". V2: Add performance data. --- include/linux/ptr_ring.h | 25 ++++++++++++++++--------- 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h index 808f9d3..db9c282 100644 --- a/include/linux/ptr_ring.h +++ b/include/linux/ptr_ring.h @@ -261,8 +261,7 @@ static inline void __ptr_ring_discard_one(struct ptr_ring *r) /* Note: we must keep consumer_head valid at all times for __ptr_ring_empty * to work correctly. */ - int consumer_head = r->consumer_head; - int head = consumer_head++; + int consumer_head = r->consumer_head + 1;

/* Once we have processed enough entries invalidate them in * the ring all at once so producer can reuse their space in the ring. @@ -271,19 +270,27 @@ static inline void __ptr_ring_discard_one(struct ptr_ring *r) */ if (unlikely(consumer_head - r->consumer_tail >= r->batch || consumer_head >= r->size)) { + int tail = r->consumer_tail; + + if (unlikely(consumer_head >= r->size)) { + r->consumer_tail = 0; + WRITE_ONCE(r->consumer_head, 0); + } else { + r->consumer_tail = consumer_head; + WRITE_ONCE(r->consumer_head, consumer_head); + } + /* Zero out entries in the reverse order: this way we touch the * cache line that producer might currently be reading the last; * producer won't make progress and touch other cache lines * besides the first one until we write out all entries. */ - while (likely(head >= r->consumer_tail)) - r->queue[head--] = NULL; - r->consumer_tail = consumer_head; - } - if (unlikely(consumer_head >= r->size)) { - consumer_head = 0; - r->consumer_tail = 0; + while (likely(--consumer_head >= tail)) + r->queue[consumer_head] = NULL; + + return; } + /* matching READ_ONCE in __ptr_ring_empty for lockless tests */ WRITE_ONCE(r->consumer_head, consumer_head); }