perf_event_open-如何监视多个事件
有谁知道如何设置perf_event_attr
可触发PMU通过以下方式监视多个(类型)事件的结构perf_event_open()
?
像一样perf record -e cycles,faults
ls,它具有两种不同的事件类型(PERF_TYPE_HARDWARE和PERF_TYPE_SOFTWARE),但是在perf_event_open的联机帮助页上的示例中,perf_event_attr.type
只能分配单个值。
任何建议将不胜感激,谢谢!
感谢@gudok为我指明方向,但结果似乎有些异常。如下所示的演示程序(用于测量整个系统的CPU周期和缓存未命中):
#define _GNU_SOURCE#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <string.h>
#include <sys/ioctl.h>
#include <linux/perf_event.h>
#include <linux/hw_breakpoint.h>
#include <asm/unistd.h>
#include <errno.h>
#include <stdint.h>
#include <inttypes.h>
#include <time.h>
struct read_format {
uint64_t nr;
struct {
uint64_t value;
uint64_t id;
} values[];
};
int main(int argc, char* argv[]) {
struct perf_event_attr pea;
int fd1, fd2;
uint64_t id1, id2;
uint64_t val1, val2;
char buf[4096];
struct read_format* rf = (struct read_format*) buf;
int i,j;
struct timespec time, time2;
time.tv_sec = 1;
time.tv_nsec = 0;
memset(&pea, 0, sizeof(struct perf_event_attr));
pea.type = PERF_TYPE_HARDWARE;
pea.size = sizeof(struct perf_event_attr);
pea.config = PERF_COUNT_HW_CPU_CYCLES;
pea.disabled = 1;
pea.exclude_kernel = 1;
pea.exclude_hv = 1;
pea.read_format = PERF_FORMAT_GROUP | PERF_FORMAT_ID;
fd1 = syscall(__NR_perf_event_open, &pea, 0, -1, -1, 0);
ioctl(fd1, PERF_EVENT_IOC_ID, &id1);
memset(&pea, 0, sizeof(struct perf_event_attr));
pea.type = PERF_TYPE_HARDWARE;
pea.size = sizeof(struct perf_event_attr);
pea.config = PERF_COUNT_HW_CACHE_MISSES;
pea.disabled = 1;
pea.exclude_kernel = 1;
pea.exclude_hv = 1;
pea.precise_ip = 2; // want to using PEBS
pea.read_format = PERF_FORMAT_GROUP | PERF_FORMAT_ID;
fd2 = syscall(__NR_perf_event_open, &pea, 0, -1, fd1 /*!!!*/, 0);
ioctl(fd2, PERF_EVENT_IOC_ID, &id2);
ioctl(fd1, PERF_EVENT_IOC_RESET, PERF_IOC_FLAG_GROUP);
ioctl(fd1, PERF_EVENT_IOC_ENABLE, PERF_IOC_FLAG_GROUP);
while (1) {
nanosleep(&time, &time2);
//ioctl(fd1, PERF_EVENT_IOC_DISABLE, PERF_IOC_FLAG_GROUP);
read(fd1, buf, sizeof(buf));
for (i = 0; i < rf->nr; i++) {
if (rf->values[i].id == id1) {
val1 = rf->values[i].value;
} else if (rf->values[i].id == id2) {
val2 = rf->values[i].value;
}
}
printf("cpu cycles: %"PRIu64"\n", val1);
printf("cache misses: %"PRIu64"\n", val2);
}
return 0;
}
输出为:
cpu cycles: 120 // Just have about 120 CPU cycles in a secondcache misses: 0 // and doesn't have any cache miss?
cpu cycles: 233
cache misses: 0
cpu cycles: 352
cache misses: 0
cpu cycles: 455
cache misses: 0
cpu cycles: 562
cache misses: 0
cpu cycles: 673
cache misses: 0
cpu cycles: 794
cache misses: 0
cpu cycles: 907
cache misses: 0
cpu cycles: 1011
cache misses: 0
cpu cycles: 1129
cache misses: 3
cpu cycles: 1269
cache misses: 4
cpu cycles: 1423
回答:
有点棘手。
我们照常创建第一个计数器。此外,我们通过PERF_FORMAT_GROUP
并PERF_FORMAT_ID
能够同时使用多个计数器。这个柜台将是我们的小组组长。
struct perf_event_attr pea;int fd1, fd2;
uint64_t id1, id2;
memset(&pea, 0, sizeof(struct perf_event_attr));
pea.type = PERF_TYPE_HARDWARE;
pea.size = sizeof(struct perf_event_attr);
pea.config = PERF_COUNT_HW_CPU_CYCLES;
pea.disabled = 1;
pea.exclude_kernel = 1;
pea.exclude_hv = 1;
pea.read_format = PERF_FORMAT_GROUP | PERF_FORMAT_ID;
fd1 = syscall(__NR_perf_event_open, &pea, 0, -1, -1, 0);
接下来,我们检索第一个计数器的标识符:
ioctl(fd1, PERF_EVENT_IOC_ID, &id1);
第二个(以及所有其他计数器)以相同的方式创建,只有一个例外:我们将fd1
值作为组长参数传递:
memset(&pea, 0, sizeof(struct perf_event_attr));pea.type = PERF_TYPE_SOFTWARE;
pea.size = sizeof(struct perf_event_attr);
pea.config = PERF_COUNT_SW_PAGE_FAULTS;
pea.disabled = 1;
pea.exclude_kernel = 1;
pea.exclude_hv = 1;
pea.read_format = PERF_FORMAT_GROUP | PERF_FORMAT_ID;
fd2 = syscall(__NR_perf_event_open, &pea, 0, -1, fd1, 0); // <-- here
ioctl(fd2, PERF_EVENT_IOC_ID, &id2);
接下来,我们需要声明一个数据结构以一次读取多个计数器。您必须根据传递给的标志声明不同的字段集perf_event_open
。手册页提到了所有可能的字段。在我们的例子中,我们通过PERF_FORMAT_ID
了添加id
字段的标志。这将使我们能够区分不同的计数器。
struct read_format { uint64_t nr;
struct {
uint64_t value;
uint64_t id;
} values[/*2*/];
};
现在我们将标准配置文件称为ioctl:
ioctl(fd1, PERF_EVENT_IOC_RESET, PERF_IOC_FLAG_GROUP);ioctl(fd1, PERF_EVENT_IOC_ENABLE, PERF_IOC_FLAG_GROUP);
do_something();
ioctl(fd1, PERF_EVENT_IOC_DISABLE, PERF_IOC_FLAG_GROUP);
最后,我们从组长文件描述符中读取计数器。这两个计数器都以read_format
我们声明的单一结构返回:
char buf[4096];struct read_format* rf = (struct read_format*) buf;
uint64_t val1, val2;
read(fd1, buf, sizeof(buf));
for (i = 0; i < rf->nr; i++) {
if (rf->values[i].id == id1) {
val1 = rf->values[i].value;
} else if (rf->values[i].id == id2) {
val2 = rf->values[i].value;
}
}
printf("cpu cycles: %"PRIu64"\n", val1);
printf("page faults: %"PRIu64"\n", val2);
以下是完整的程序清单:
#define _GNU_SOURCE#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <string.h>
#include <sys/ioctl.h>
#include <linux/perf_event.h>
#include <linux/hw_breakpoint.h>
#include <asm/unistd.h>
#include <errno.h>
#include <stdint.h>
#include <inttypes.h>
struct read_format {
uint64_t nr;
struct {
uint64_t value;
uint64_t id;
} values[];
};
void do_something() {
int i;
char* ptr;
ptr = malloc(100*1024*1024);
for (i = 0; i < 100*1024*1024; i++) {
ptr[i] = (char) (i & 0xff); // pagefault
}
free(ptr);
}
int main(int argc, char* argv[]) {
struct perf_event_attr pea;
int fd1, fd2;
uint64_t id1, id2;
uint64_t val1, val2;
char buf[4096];
struct read_format* rf = (struct read_format*) buf;
int i;
memset(&pea, 0, sizeof(struct perf_event_attr));
pea.type = PERF_TYPE_HARDWARE;
pea.size = sizeof(struct perf_event_attr);
pea.config = PERF_COUNT_HW_CPU_CYCLES;
pea.disabled = 1;
pea.exclude_kernel = 1;
pea.exclude_hv = 1;
pea.read_format = PERF_FORMAT_GROUP | PERF_FORMAT_ID;
fd1 = syscall(__NR_perf_event_open, &pea, 0, -1, -1, 0);
ioctl(fd1, PERF_EVENT_IOC_ID, &id1);
memset(&pea, 0, sizeof(struct perf_event_attr));
pea.type = PERF_TYPE_SOFTWARE;
pea.size = sizeof(struct perf_event_attr);
pea.config = PERF_COUNT_SW_PAGE_FAULTS;
pea.disabled = 1;
pea.exclude_kernel = 1;
pea.exclude_hv = 1;
pea.read_format = PERF_FORMAT_GROUP | PERF_FORMAT_ID;
fd2 = syscall(__NR_perf_event_open, &pea, 0, -1, fd1 /*!!!*/, 0);
ioctl(fd2, PERF_EVENT_IOC_ID, &id2);
ioctl(fd1, PERF_EVENT_IOC_RESET, PERF_IOC_FLAG_GROUP);
ioctl(fd1, PERF_EVENT_IOC_ENABLE, PERF_IOC_FLAG_GROUP);
do_something();
ioctl(fd1, PERF_EVENT_IOC_DISABLE, PERF_IOC_FLAG_GROUP);
read(fd1, buf, sizeof(buf));
for (i = 0; i < rf->nr; i++) {
if (rf->values[i].id == id1) {
val1 = rf->values[i].value;
} else if (rf->values[i].id == id2) {
val2 = rf->values[i].value;
}
}
printf("cpu cycles: %"PRIu64"\n", val1);
printf("page faults: %"PRIu64"\n", val2);
return 0;
}
以上是 perf_event_open-如何监视多个事件 的全部内容, 来源链接: utcz.com/qa/421025.html