V$osstat and V$SYS_TIME_MODEL question

Question

Hi there !
I have a function osstat, which take stats from the os using v$osstat (credits for the procedure to a person, I regret to say, that I cant remember his name). But since we have 9 databases on the same server (and we dont have access to the server os itself (outsourcing stinks), we often would like to know more about cpu, waits etc. And one of the procedures we use is the osstat.
I have tried to combine it with V$SYS_TIME_MODEL in oder to se how much of the OS CPU time comes from the instance I am on at the moment, but I'm not able to figure out how to do it exaclty.
This is my code:
DROP TYPE OSSTAT_RECORD;
CREATE OR REPLACE TYPE osstat_record IS OBJECT (
  date_time_from TIMESTAMP,
  date_time_to TIMESTAMP,
  idle_time NUMBER,
  user_time NUMBER,
  sys_time NUMBER,
  iowait_time NUMBER,
  nice_time NUMBER,
  instance_cpu_time NUMBER
DROP TYPE OSSTAT_TABLE;
CREATE OR REPLACE TYPE osstat_table AS TABLE OF osstat_record;
CREATE OR REPLACE FUNCTION osstat(p_interval IN NUMBER default 5, p_count IN NUMBER default 2, p_dec in number default 0)
   RETURN osstat_table
   PIPELINED
IS
  l_t1 osstat_record;
  l_t2 osstat_record;
  l_out osstat_record;
  l_num_cpus NUMBER;
  l_total NUMBER;
  l_instance NUMBER;
BEGIN
  l_t1 := osstat_record(NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL);
  l_t2 := osstat_record(NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL);
  SELECT value
  INTO l_num_cpus
  FROM v$osstat
  WHERE stat_name = 'NUM_CPUS';
  FOR i IN 1..p_count+1
  LOOP
    SELECT systimestamp, sum(decode(stat_name,'IDLE_TIME', value, NULL)) as idle_time,
           sum(decode(stat_name,'USER_TIME', value, NULL)) as user_time,
           sum(decode(stat_name,'SYS_TIME', value, NULL)) as sys_time,
           sum(decode(stat_name,'IOWAIT_TIME', value, NULL)) as iowait_time,
           sum(decode(stat_name,'NICE_TIME', value, NULL)) as nice_time
    INTO l_t2.date_time_to, l_t2.idle_time, l_t2.user_time, l_t2.sys_time, l_t2.iowait_time, l_t2.nice_time
    FROM v$osstat
    WHERE stat_name in ('IDLE_TIME','USER_TIME','SYS_TIME','IOWAIT_TIME','NICE_TIME');
    select value/100000
    into l_t2.instance_cpu_time
    from  V$SYS_TIME_MODEL
    where stat_name = 'DB time';
    l_out := osstat_record(l_t1.date_time_from, systimestamp,
                           (l_t2.idle_time-l_t1.idle_time)/l_num_cpus/p_interval,
                           (l_t2.user_time-l_t1.user_time)/l_num_cpus/p_interval,
                           (l_t2.sys_time-l_t1.sys_time)/l_num_cpus/p_interval,
                           (l_t2.iowait_time-l_t1.iowait_time)/l_num_cpus/p_interval,
                           (l_t2.nice_time-l_t1.nice_time)/l_num_cpus/p_interval,
                           ((l_t2.instance_cpu_time-l_t1.instance_cpu_time)/100));  --- >>  Should I divide by no of cpus here as well???  Or ???
    l_total := l_out.idle_time+l_out.user_time+l_out.sys_time+l_out.iowait_time+nvl(l_out.nice_time,0);
    if l_out.user_time > 0 then
       l_instance := (l_out.instance_cpu_time*100)/l_total;   ->> instance in percent of the total cputime
    else
       l_instance := 0;
    end if;
    if i > 1 then
    PIPE ROW(osstat_record(l_t1.date_time_to, systimestamp,
                           trunc((l_out.idle_time/l_total*100),p_dec),
                           trunc((l_out.user_time/l_total*100),p_dec),
                           trunc((l_out.sys_time/l_total*100),p_dec),
                           trunc((l_out.iowait_time/l_total*100),p_dec),
                           trunc((l_out.nice_time/l_total*100),p_dec),
                           trunc(l_instance,p_dec)));
    end if;
    l_t1 := l_t2;
    sys.dbms_lock.sleep(p_interval);
  END LOOP;
  RETURN;
END;
/I get ie a USER CPU Time of 15% fo a given interval of 5 mins - and a cputime for the instance of 50 - and others are 5% and 1%.
My brain has stopped working now .... I'm stuck
Mette

Answer 1

mettemusens wrote:
Hi there !
I have a function osstat, which take stats from the os using v$osstat (credits for the procedure to a person, I regret to say, that I cant remember his name). But since we have 9 databases on the same server (and we dont have access to the server os itself (outsourcing stinks), we often would like to know more about cpu, waits etc. And one of the procedures we use is the osstat.
I have tried to combine it with V$SYS_TIME_MODEL in oder to se how much of the OS CPU time comes from the instance I am on at the moment, but I'm not able to figure out how to do it exaclty.
This is my code:
select value/100000
into l_t2.instance_cpu_time
from  V$SYS_TIME_MODEL
where stat_name = 'DB time';
Mette,
I haven't thought through your approach, but at a quick glance I noticed that you use *"DB time"* for your "Instance CPU time" measure. Shouldn't this be *"DB CPU"* instead? "DB time" contains all other time spent as well, like waiting for I/O etc.
Regards,
Randolf
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