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stress@stresslinux:~>;sudo rm /tmp/sensors stress@stresslinux:~>;sudo sl-wizard.sh |
This is not an ordinary stripped-down Linux. It was built with SUSE Studio, and is based on OpenSUSE.
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Stresslinux uses the Fn keys in an interesting way. There are 6 ordinary ttys on F1-F6, and it boots to tty1 on F1. The rest are normal login ttys. On US keyboards you can switch between these with ALT+Fn. (STRG+Fn on German keyboards, which is the same as CTRL+Fn.) F10 displays eth0 throughput (see above), F11 shows hard disk temperatures, and F12 displays lm-sensors readings.
What to Do : The Main Task:
Now that Stresslinux is booted up and you have gazed upon your eth0 and sensor outputs, what's next? Let's spend some time with the stress command, because that is a good general-purpose workload generator. It operates by siccing a bunch of hogs on your system. This simple invocation puts a light load on the CPU, I/O, memory, and hard drive:
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stress --cpu 1000 --io 4 --vm 2 --hdd 4 --timeout 15m --verbose |
When it finishes with "successful run completed" that means there were no errors. If it did detect errors, it would either try to tell you what they were, or tell you to examine the syslog. Let's walk through this so we know what it's doing.
--cpu 1000 tells it to fork 1000 processes. Each process calculates the square root of a random number (by calling the sqrt() and rand functions) in a loop that stops at the end of your timeout, or when you stop it with CTRL+c. This is similar, a way to keep the CPU constantly busy. 1000 processes surely put some load !!!
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--vm 2 thrashes your RAM by forking 2 processes to allocate and release memory. (Looping malloc() and free().) You can control the load on your memory with the --vm-bytes option.
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stress --vm 2 --vm-bytes 3G --vm-hang --timeout 60s |
Be careful with this because thrashing your memory can make your system hang. The vm option allocates and releases memory; the vm-hang simulates low memory conditions by having each hog process go to sleep, rather than releasing memory. This above example hogs 3 gigabytes of memory:
--hdd 4 pummels your hard drive with writes, by calling the write function in a loop. The default file size is 1GB, and you can specify any size with the --hdd-bytes option, for example --hdd-bytes 5G writes a 5 gigabyte file.
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--timeout 30s tells stress to stop after 30 seconds. Or whatever time you want, of course, using s,m,h,d,y (seconds, minutes, hours, days, years). Always set a timeout, because this is your protection from the system locking up and becoming inaccessible. stress runs in userspace and can't cause any damage, but it would be sad to have to reboot to stop it.
--verbose makes it spit out many lines telling what it is doing.
stress is tidy and cleans up after itself, so you shouldn't have to worry about leftover hogs running amok. The documentation on stress isn't exactly lavish, and the most complete help is in info stress.