sysbench是一个非常经典的综合性能测试工具，它支持CPU，IO，内存，尤其是数据库的性能测试。那它是怎么做到通用性的呢，总结一句话是大量运用了重载的方法。

sysbench总体架构

sysbench是一个总体框架，它用来操作各个测性能的计算，那各个部门只需要做的一件事情是声明需要的实现。只要理解了这三个struct就可以了：

/* 某个测试用例的整体结构 */
typedef struct sb_test
{const char        *sname;const char        *lname;/* 下面有具体说明 */sb_operations_t   ops;sb_builtin_cmds_t builtin_cmds;sb_arg_t          *args;sb_list_item_t    listitem;
} sb_test_t;
/* 某个测试用例的具体操作实现结构 */
typedef struct
{sb_op_init            *init;            /* initialization function */sb_op_prepare         *prepare;         /* called after timers start,  butbefore thread execution */sb_op_thread_init     *thread_init;     /* thread initialization(called when each thread starts) */sb_op_print_mode      *print_mode;      /* print mode function */sb_op_next_event      *next_event;      /* event generation function */sb_op_execute_event   *execute_event;   /* event execution function */sb_op_report          *report_intermediate; /* intermediate reports handler */sb_op_report          *report_cumulative;   /* cumulative reports handler */sb_op_thread_run      *thread_run;      /* main thread loop */sb_op_thread_done     *thread_done;     /* thread finalize function */sb_op_cleanup         *cleanup;         /* called after exit from thread,but before timers stop */ sb_op_done            *done;            /* finalize function */
} sb_operations_t;
/* 某个测试用例的三阶段实现结构 */
typedef struct
{sb_builtin_cmd_func_t *help;  /* print help */sb_builtin_cmd_func_t *prepare; /* prepare for the test */sb_builtin_cmd_func_t *run;   /* run the test */sb_builtin_cmd_func_t *cleanup; /* cleanup the test database, files, etc. */
} sb_builtin_cmds_t;复制代码

拿最简单的CPU性能计算举例，它需要实现的是：

static sb_test_t cpu_test =
{.sname = "cpu", /*case简称*/.lname = "CPU performance test",/*case全称*/.ops = {.init = cpu_init, /* 初始化case */.print_mode = cpu_print_mode, /* case启动前，做说明 */.next_event = cpu_next_event, /* 拿到下一个event的数据 */.execute_event = cpu_execute_event, /* 具体执行这个event */.report_cumulative = cpu_report_cumulative,  /* 阶段性报告输出 */.done = cpu_done /* case结束后，处理干净 */},.args = cpu_args /*子case需要的参数说明*/
};复制代码

看到这个后，把一个case需要做的事情描述很清楚了，从需要什么参数，到初始化，逐个event执行，函数定义很清晰。sysbench的其他case也都这样需要一个完整的结构说明，如io操作，则需要多一个case的prepare和cleandown声明。
那sysbench的完整流程是怎样呢？黄色部分是测试用例需要实现的。

至此，可以清晰地看到sysbench的框架还是非常好理解。
上面struct里面有个event概念，不同的测试event的定义都不一样：比如CPU的测试case，一个event是完成求得小于某数（默认10000）的所有质数。比如fileio的测试case，一次read或者一次write操作就是一个event。

sysbench的线程介绍

worker_thread具体实现是怎样呢：欣赏下sysbench.c里面某子线程是如何执行的，代码非常清晰易懂：

static int thread_run(sb_test_t *test, int thread_id)
{sb_event_t        event;int               rc = 0;while (sb_more_events(thread_id) && rc == 0){event = test->ops.next_event(thread_id);if (event.type == SB_REQ_TYPE_NULL)break;sb_event_start(thread_id);rc = test->ops.execute_event(&event, thread_id);sb_event_stop(thread_id);}return rc;
}复制代码

intermediate_report线程：周期性输出性能数据，参数项为：--report-interval=N,对CPU的测试用例举例：sysbench cpu --report-interval=1,截取部分输出结果如下：

Threads started![ 1s ] thds: 1 eps: 922.10 lat (ms,95%): 1.08
[ 2s ] thds: 1 eps: 925.19 lat (ms,95%): 1.08
[ 3s ] thds: 1 eps: 926.00 lat (ms,95%): 1.08
[ 4s ] thds: 1 eps: 926.00 lat (ms,95%): 1.08
[ 5s ] thds: 1 eps: 926.00 lat (ms,95%): 1.08
[ 6s ] thds: 1 eps: 926.00 lat (ms,95%): 1.08
[ 7s ] thds: 1 eps: 925.00 lat (ms,95%): 1.08
[ 8s ] thds: 1 eps: 926.02 lat (ms,95%): 1.08
[ 9s ] thds: 1 eps: 925.99 lat (ms,95%): 1.08
[ 10s ] thds: 1 eps: 924.98 lat (ms,95%): 1.08复制代码

每一秒输出一个结果，eps是每一秒的event数，lat单位是毫秒，95分位延迟数据是1.08

checkpoints_report线程：如果嫌周期性输出不够多，那么可以在某几个时间点整体输出，参数项为: --report-checkpoints=[LIST,...]
还是对CPU测试用例举例：sysbench cpu --report-checkpoints=3,8 run,截取部分输出结果如下：

Threads started![ 3s ] Checkpoint report:
CPU speed:events per second:   923.01General statistics:total time:                          3.0001stotal number of events:              2771Latency (ms):min:                                  1.08avg:                                  1.08max:                                  1.2295th percentile:                      1.08sum:                               3000.88Threads fairness:events (avg/stddev):           2773.0000/0.00execution time (avg/stddev):   3.0009/0.00[ 8s ] Checkpoint report:
CPU speed:events per second:   924.47General statistics:total time:                          8.0001stotal number of events:              4622Latency (ms):min:                                  1.08avg:                                  1.08max:                                  1.1695th percentile:                      1.08sum:                               4998.04Threads fairness:events (avg/stddev):           4621.0000/0.00execution time (avg/stddev):   4.9980/0.00复制代码

tx_rate_controll线程，控制每秒输出量的一个线程：参数项为: --rate=N,默认是不做控制的。
还是拿CPU测试用例举例，控制每秒跑10个event：sysbench cpu run --rate=10,截取部分输出结果如下：

Running the test with following options:
Number of threads: 1
Target transaction rate: 10/sec
Initializing random number generator from current timePrime numbers limit: 10000Initializing worker threads...Threads started!CPU speed:events per second:     8.87 #没那么精准哈复制代码

输出速率控制在哪里呢？眼尖的人马上可以看到是在sb_more_events函数。那sb_more_events函数主要是做什么呢：