System performance

Evidence-Based Performance Analysis and Tuning

Real-world performance problems are not solvable in 5 minutes with a short list of random suggestions.

Instead, you must step back, understand the issues, and then make suggestions that have two key qualities:

• The suggestions are based on evidence.
• There is a metric that can be measured both before and after the change.

 

System Component Model

(CPU(Kernel)+ RAM)------------NIC---------------LAN----------Network

                                       |                      |________________NFS

                                       |_____________________________(DISK(Swap))

 

Initially, see if there are common problems that may have been overlooked.

performance always degrades when the system starts swapping.

network performance can be poor due to bad hardware or a bad negotiation.

polling for IO, instead of using poll/select.