[SOLVED] Httpd.exe *32 process behaviour under (HTTP) DDoS load

[xazz]

So I was experimenting with (HTTP) DDoS attacks on my local test webserver with various number of packets per second (75, 150, 300 etc.). With the first two attacks (75, 150) Performance Monitor (Perfmon) showed though high (CPU ~90%) but still consistent (stable) usage of resources under load.

But with the third attack (300) Perfmon showed several CPU and RAM DIPS (on DIP 3 CPU usage even fell to 1-3% for about 16 seconds) and knowing that httpd.exe *32 (Apache HTTP Server) process was the main resource consumer I am wondering what could be the reason for these DIPS.

Screenshots

- Was the process trying to optimize resource usage under load?

P.S.: The DIPS continue on with attacks greater that 300 packets/s (450,600,750,900 etc.)

 

[nigelivey]

What was the frequency of your CPU during the tests, did it turbo only when under load for the final test?

 

[xazz]

• CPU: Intel Core i5 M460 2.53Ghz
• RAM: 4GB
• NET: JMicron PCI Express Gigabit Ethernet Adapter

Yes, CPU spiked (~90% +) only under load (right after DDoS Start) and DIPS happened only with HTTP DDoS (GET requests) onward from 300 to 900.
Here are the remaining screenshots with CPU, RAM DIPS (450 to 900).

Screenshots

 

[Alabalcho]

It could be that your HTTPD daemon just started dropping frames...