RE: CPU upgrade caused application slow down

You have to be more precise describing what slowed down. What is your =
way of measuring the application response time?
Is the app running on the server hosting the DB?=20

That table that you re-organized, is it being accessed using indexes?

Waleed

-----Original Message-----
From: zhu chao [mailto:chao_ping@xxxxxxxxxxx]
Sent: Friday, April 30, 2004 5:42 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: CPU upgrade caused application slow down


Hi, list friends:
   =20
    We did a server upgrade this month. And we hit something we cannot =
understand. So we refer to you guys for help , hoping you have similar =
experienceJ
            We did a server upgrade this month. Biddb upgrade from =
8*900MHZ FireV880 to 8*1200MHZ Fire V880, SAN HBA card also upgraded =
from 1gb to 2gb.

             System Level parameter like /etc/system, oracle initsid.ora =
are same for biddb before and after server upgrade.(except for processes =
increased from 800 to 1200).SGA of database is reduced from 11.5GB to =
11GB.But disk read did not increase as we reorganized a table with 29M =
records to 13M records(CTAS, drop old table).

                       The upgrade result is good,  CPU usage dropped =
about 20%-30% percent.  But the application response time does not drop. =
It even slow down slightly. :(.  This is not what we expect. Statspack  =
does not show much difference before and after upgrade(load profile , =
wait event etc).

            Later we did some test, hoping to find out how can this =
happen, but we cannot draw a conclusion from our test result.


  1.. According to Cary Millsap=A1=AFs theory, upgrade CPU *CAN* make =
performance worse. In his case, SQL*Net was the bottleneck. Our server =
network traffic is only at 15-20Mb/Second. This seems not like the =
bottleneck, Though from 10046 trace report, sqlnet wait is the NO.1 wait =
event, but this is normal for most applications.  I also tried to change =
the tnsnames.ora and listener.ora with larger SDU/TDU of 8KB, restarted =
tuxedo service and oracle listener. And compare the performance data =
leter. This does not make much difference for application response time. =


  2.. We did some pure simple SQL test. Result in appendix 1. SAME SQL =
in 1200MHZ CPU does run faster.=20
=20
  2.. We write a simple tuxedo service run the same SQL for 1000 times. =
Everytime the SQL is transferred through SQL*Net and result is fetched =
into host variable. The result still shows that it runs faster on =
1200MHZ CPU. The average response time in 1200MHZ server is 12.12ms ,and =
the average response time in 900mhz server is 14.20ms.=20
=20

We cannot find out the root cause of application slow down. Though the =
slow down is very small (around 5% percent, maybe), it is not happy to =
see such result and we are interested in knowing why.

If you have similar experience before and do find out how this can =
happen, we would be very happy.

=20

Thanks for your time.

Regards

Zhu Chao.

=20

=20

=20

Appendix 1:

Eachdb2: (900mhz CPU)

=20

  1  declare v_result number;

  2  begin

  3  for x in 1..1000 loop

  4  select count(*) into v_result from testsystem;

  5  end loop;

  6* end;

09:38:13   7  /

=20

PL/SQL procedure successfully completed.

=20

Elapsed: 00:02:17.37

09:40:31 SQL>

=20

Biddb (1200MHZ CPU)

=20

  1  declare v_result number;

  2  begin

  3  for x in 1..1000 loop

  4  select count(*) into v_result from testsystem;

  5  end loop;

  6* end;

09:42:29 SQL>=20

09:42:30 SQL>=20

09:42:30 SQL> /

=20

PL/SQL procedure successfully completed.

Elapsed: 00:01:57.99

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