more stress with stress-ng

Since my last article about stress-ng I have been adding a few more stress mechanisms to stress-ng:

• file locking - exercise file locking with one or more processes (the more processes the better).
• fallocate - this allocates a 4MB file, sync's, truncates to zero size and syncs repeatedly
• yield - this loops on sched_yield() to repeatedly relinquish the CPU forcing a high context switch rate when run with multiple yielding processes.

Also, I have added some new features to tweak scheduling, I/O characteristics and memory allocations of the running stress processes:

• --sched and --sched-prio options to specify the scheduler type and priority
• --ionice-class and --ionice-level options to tweak I/O niceness
• --vm-populate option to populate (pre-fault) page tables for a mapping for the --vm stress test.

If I think of other mechanisms to stress the kernel I will add them, but for now, stress-ng is becoming almost feature complete.