Re: We quadrupled hardware power and reduced performance

From: Baisong Wei[MSFT] (v-baiwei_at_online.microsoft.com)
Date: 03/17/04


Date: Wed, 17 Mar 2004 13:01:20 GMT

Hi Randolph,

As for all the components work as a whole, we could not be sure that one
part's improvement could bring a overall improvement. Though performance is
always a big issue of SQL Server, we do have some general rules to
troubleshoot it. Here I just want to add some information on that.

When we face a performance issue, we should have a baseline of it ( for
your case it would be a hardware improvement should bring a overall
improvement of the whole system) and we should narrow down the problem to
the bottleneck from Application/Query/Database Design -> Operating
Environment-> Hardware. In your case, the later 2 changed, and the whole
system does not meet you expectation. So, we should make the expectation
clear: Query slow? CPU high? In you case, it seems that the high CPU
utilization is your concern, and I am not sure if this has bring a impact
to your application performace. Then, some tools are needed to check why it
is so high. I would say that in some sense, the CPU is driven by the other
subsystems. In other words, bottlenecks in memory or I/O will often first
appear as a CPU bottleneck. Because of this ver issue, the best process for
evaluation system perfomance is to first analyze memory, thant the I/O
subsystem and finally the processor. This is an important concept in that a
shortage of memory will tend to drive a significant percentage of kernel
time. This is not to say that you should completely ignore the processor
when first evaluation system performance. This is especially true in a
"hang" situation.

There is some counters that you might use to monitor:
%Processor time
%Priviliged time
%User time
%DPC time
%interrupt time
DPCs Queued/sec
Interrupts/sec
Processor qurue length, ect.

and then, you'd better determine SQL Server's contribution to the CPU
bottleneck.

As for more detailed information and method to troubleshooting performance
issue, I would recommend the following articles for your reference.

HOW TO: Troubleshoot Application Performance Issues
http://support.microsoft.com/default.aspx?scid=kb;en-us;298475

Support WebCast: How to Collect and Analyze Performance Data in Microsoft
SQL Server
http://support.microsoft.com/?id=324692

How To Gather Information for Effective Troubleshooting of Performance
Issues
http://support.microsoft.com/default.aspx?scid=http://support.microsoft.com:
80/support/kb/articles/Q175/6/58.ASP&NoWebContent=1

Hope this helps.

Sincerely Yours

Baisong Wei
Microsoft Online Support
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