Performance Analysis by Tracing Side Effects

People sometimes claim that if a performance measure has not been recorded directly, then it is not possible to report on it.  Need to know how long a batch job took to run? That’s ok – I have a table that tells me job run times.  But if you need to know how much work a batch job did?  We don’t record throughput, they say.  This may be followed by a suggestion that they could add log messages or something like that. Continue reading

The Importance of Baselining

Baselining is used in IT to record some measurement(s) with a view to comparison later.  If you know some statistic on one day – say for example the average CPU usage on a server, then you can measure the same data-point the next day and draw a comparison.  It is often used so that you can measure the impact of some change or other, and assess its success.

Today, I want to talk about the importance of baselining with a counter-example – what can happen if you don’t baseline before making changes to a system; especially where those changes were intended to improve performance! Continue reading