Re: CPU upgrade caused application slow down

  • From: Tim Gorman <tim@xxxxxxxxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Fri, 30 Apr 2004 04:12:12 -0600

Zhu Chao,

Sustained rates of 15-20 Mbytes/sec is absolute network saturation if you'r=
running 100BaseT - don=B9t forget that 100 Mbits/sec is 12.5 Mbytes/sec.  Eve=
if the network segment closest to the server is GigE, you might have a
network segment somewhere in the mix running at 100BaseT, perhaps?

Cary's remarks aren't theory, of course.  Making one component of the stack
of technology much faster will almost certainly cause a bottleneck in
another component.  Think of a 10-mile (16 km) roadway where the first 6
miles (10 km) are expanded to 4 lanes while the remainder is left at 2
lanes.  That was the situation in my hometown (Evergreen, Colorado) some
years ago -- guess whether the roadway expansion helped improve traffic flo=
or caused massive backups where the lanes reduced from 4 to 2...?

Just some thoughts...


> 1.. According to Cary Millsap=A1=AFs theory, upgrade CPU *CAN* make performan=
> worse. In his case, SQL*Net was the bottleneck. Our server network traffi=
c is
> only at 15-20Mb/Second. This seems not like the bottleneck, Though from 1=
> trace report, sqlnet wait is the NO.1 wait event, but this is normal for =
> applications.  I also tried to change the tnsnames.ora and listener.ora w=
> larger SDU/TDU of 8KB, restarted tuxedo service and oracle listener. And
> compare the performance data leter. This does not make much difference fo=
> application response time.
> 2.. We did some pure simple SQL test. Result in appendix 1. SAME SQL in
> 1200MHZ CPU does run faster.
> 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 in=
> host variable. The result still shows that it runs faster on 1200MHZ CPU.=
> average response time in 1200MHZ server is 12.12ms ,and the average respo=
> time in 900mhz server is 14.20ms.

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