[20190402]对比_mutex_wait_scheme不同模式cpu消耗.txt

[20190402]对比_mutex_wait_scheme不同模式cpu消耗.txt

--//前几天做了sql语句在mutexes上的探究.今天对比不同_mutex_wait_scheme模式cpu消耗.

1.环境:
SYS@book> @ hide mutex
NAME                DESCRIPTION        DEFAULT_VALUE SESSION_VALUE SYSTEM_VALUE
------------------- ------------------ ------------- ------------- ------------
_mutex_spin_count   Mutex spin count   TRUE          255           255
_mutex_wait_scheme  Mutex wait scheme  TRUE          2             2
_mutex_wait_time    Mutex wait time    TRUE          1             1

--//注:_mutex_wait_time=1,相当1厘秒.

SCOTT@book> @ ver1
PORT_STRING                    VERSION        BANNER
------------------------------ -------------- --------------------------------------------------------------------------------
x86_64/Linux 2.4.xx            11.2.0.4.0     Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

$ cat m2.txt
set verify off
column a noprint new_value v_a;
--select mod ( &&3 ,3) a  from dual ;
--alter session set optimizer_index_cost_adj= &&3;
host sleep $(echo &&3/50| bc -l )
insert into job_times values ( sys_context ('userenv', 'sid') ,dbms_utility.get_time ,'&&2') ;
commit ;
declare
v_id number;
v_d date;
begin
    for i in 1 .. &&1 loop
        --select  1 into v_id from dual ;
        --select  sysdate into v_d from dual ;
        select deptno into v_id from dept where deptno=10;
    end loop;
end ;
/
update job_times set time_ela = dbms_utility.get_time - time_ela where sid=sys_context ('userenv', 'sid') and method='&&2';
commit;
--quit

$ seq 150 | xargs -I {}  -P 150 bash -c  "sqlplus -s -l scott/book @m2.txt 1e6 f2_150 {} >/dev/null"

SYS@book> @ mutexy 6 a31kd5tkdvvmm
      HASH SUM_SLEEPS   SUM_GETS LOCATION                       MUTEX_TYPE           MUTEX_ADDR       SQLID         KGLNAOWN C100
---------- ---------- ---------- ------------------------------ -------------------- ---------------- ------------- -------- ---------------------------------------
1692266099    2263154 4.6431E+10 kksLockDelete [KKSCHLPIN6]     Cursor Pin           000000007C88E330 a31kd5tkdvvmm          SELECT DEPTNO FROM DEPT WHERE DEPTNO=10
1692266099    2183544 4.4733E+10 kksfbc [KKSCHLFSP2]            Cursor Pin           000000007C88E330 a31kd5tkdvvmm          SELECT DEPTNO FROM DEPT WHERE DEPTNO=10
1692266099       5256  600010918 kksfbc [KKSCHLPIN1]            Cursor Pin           000000007C88E330 a31kd5tkdvvmm          SELECT DEPTNO FROM DEPT WHERE DEPTNO=10
1692266099          6   45955498 kksHeapReadUnlock [KKSCHLRDUP] Cursor Pin           000000007C88E330 a31kd5tkdvvmm          SELECT DEPTNO FROM DEPT WHERE DEPTNO=10

--//MUTEX_ADDR=000000007C88E330.

2.测试一:
--//测试_mutex_wait_scheme=2的情况:
--//session 1:
SCOTT@book> @ spid
       SID    SERIAL# PROCESS                  SERVER    SPID       PID  P_SERIAL# C50
---------- ---------- ------------------------ --------- ------ ------- ---------- --------------------------------------------------
       295          5 65222                    DEDICATED 65223       21          3 alter system kill session '295,5' immediate;

--//session 2:       
SYS@book> oradebug setmypid
Statement processed.

SYS@book> oradebug peek 0x000000007C88E330 8
[07C88E330, 07C88E338) = 00000000 00000000

SYS@book> oradebug poke 0x000000007C88E330 8 0x0000000200000127
BEFORE: [07C88E330, 07C88E338) = 00000000 00000000
AFTER:  [07C88E330, 07C88E338) = 00000127 00000002

--//session 1:
SCOTT@book> @ m2.txt 1 c1 0
1 row created.
Commit complete.
--//挂起!!

$ top -p 65223
  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
65223 oracle    20   0  857m  29m  25m S  0.3  0.0   0:00.41 oracle
--//CPU消耗0.3.

--//另外我执行如下:
SYS@book> @ mutexy 5 a31kd5tkdvvmm
      HASH SUM_SLEEPS   SUM_GETS LOCATION                       MUTEX_TYPE           MUTEX_ADDR       SQLID         KGLNAOWN C100
---------- ---------- ---------- ------------------------------ -------------------- ---------------- ------------- -------- ---------------------------------------
1692266099    2263154 4.6431E+10 kksLockDelete [KKSCHLPIN6]     Cursor Pin           000000007C88E330 a31kd5tkdvvmm          SELECT DEPTNO FROM DEPT WHERE DEPTNO=10
1692266099    2183544 4.4733E+10 kksfbc [KKSCHLFSP2]            Cursor Pin           000000007C88E330 a31kd5tkdvvmm          SELECT DEPTNO FROM DEPT WHERE DEPTNO=10
1692266099      19266  600013714 kksfbc [KKSCHLPIN1]            Cursor Pin           000000007C88E330 a31kd5tkdvvmm          SELECT DEPTNO FROM DEPT WHERE DEPTNO=10
1692266099          6   45955498 kksHeapReadUnlock [KKSCHLRDUP] Cursor Pin           000000007C88E330 a31kd5tkdvvmm          SELECT DEPTNO FROM DEPT WHERE DEPTNO=10

--//等一会...

SYS@book> @ mutexy 5 a31kd5tkdvvmm
      HASH SUM_SLEEPS   SUM_GETS LOCATION                       MUTEX_TYPE           MUTEX_ADDR       SQLID         KGLNAOWN C100
---------- ---------- ---------- ------------------------------ -------------------- ---------------- ------------- -------- ---------------------------------------
1692266099    2263154 4.6431E+10 kksLockDelete [KKSCHLPIN6]     Cursor Pin           000000007C88E330 a31kd5tkdvvmm          SELECT DEPTNO FROM DEPT WHERE DEPTNO=10
1692266099    2183544 4.4733E+10 kksfbc [KKSCHLFSP2]            Cursor Pin           000000007C88E330 a31kd5tkdvvmm          SELECT DEPTNO FROM DEPT WHERE DEPTNO=10
1692266099      26386  600013714 kksfbc [KKSCHLPIN1]            Cursor Pin           000000007C88E330 a31kd5tkdvvmm          SELECT DEPTNO FROM DEPT WHERE DEPTNO=10
1692266099          6   45955498 kksHeapReadUnlock [KKSCHLRDUP] Cursor Pin           000000007C88E330 a31kd5tkdvvmm          SELECT DEPTNO FROM DEPT WHERE DEPTNO=10

--//仅仅LOCATION=kksfbc [KKSCHLPIN1],SUM_SLEEPS数量在增加.

AFTER:  [07C88E330, 07C88E338) = 00000127 00000002
SYS@book> oradebug poke 0x000000007C88E330 8 0x0
BEFORE: [07C88E330, 07C88E338) = 00000127 00000002
AFTER:  [07C88E330, 07C88E338) = 00000000 00000000

3.测试二:
--//测试_mutex_wait_scheme=1的情况:
--//基本重复上面的步骤,不再列出执行步骤.
SYS@book> alter system set "_mutex_wait_scheme"=1 scope=memory;
System altered.

$ top -p 65223
PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
65223 oracle    20   0  857m  29m  25m S  3.0  0.0   0:01.29 oracle
--//CPU消耗3.

4.测试三:
--//测试_mutex_wait_scheme=1的情况:
--//基本重复上面的步骤,不再列出执行步骤.
SYS@book> alter system set "_mutex_wait_scheme"=0 scope=memory;
System altered.

$ top -p 65223
  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
65223 oracle    20   0  857m  29m  25m S 39.9  0.0   0:06.99 oracle

--//CPU消耗39.9

5.总结:
--//画一个表格如下:
-------------------------------------------------------------------------------------------------------
_mutex_wait_scheme     CPU使用率      描述
------------------------------------------------------------------------------------------------------
2                      .3             2秒时间内,semtimedop 182次 getrusage 2次 _mutex_spin_count=255
                       12             2秒时间内,semtimedop 167次 getrusage 2次 _mutex_spin_count=65535
1                      3              2秒时间内, select 16XX次(每次调用0.001秒).,getrusage 2次
0                      39.9           调用99次sched_yield,然后1次seelct(每次调用0.001秒).
------------------------------------------------------------------------------------------------------
--//注:这是我当前硬件条件下的测试结果,而且我一直阻塞sql语句执行并且_mutex_wait_time=1的情况.
--//一些测试数据参考链接:
http://blog.itpub.net/267265/viewspace-2639675/
http://blog.itpub.net/267265/viewspace-2640003/

原文地址:https://www.cnblogs.com/lfree/p/10641435.html