sysbench的框架实现介绍

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, but

                                         before 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;
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/
};
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;
}
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
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:   923.01

General statistics:

total time:                          3.0001s
total number of events:              2771

Latency (ms):

     min:                                  1.08
     avg:                                  1.08
     max:                                  1.22
     95th percentile:                      1.08
     sum:                               3000.88

Threads fairness:

events (avg/stddev):           2773.0000/0.00
execution time (avg/stddev):   3.0009/0.00

[ 8s ] Checkpoint report:
CPU speed:

events per second:   924.47

General statistics:

total time:                          8.0001s
total number of events:              4622

Latency (ms):

     min:                                  1.08
     avg:                                  1.08
     max:                                  1.16
     95th percentile:                      1.08
     sum:                               4998.04

Threads fairness:

events (avg/stddev):           4621.0000/0.00
execution time (avg/stddev):   4.9980/0.00

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 time

Prime numbers limit: 10000

Initializing worker threads...

Threads started!

CPU speed:

events per second:     8.87 #没那么精准哈

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：

判断是否超时，默认是10秒
判断是否到达最大event数，如果设置了的话
就是速率控制。
综上，大概介绍了sysbench框架的总体实现，关于数据库性能测试容下篇再介绍。