stress-ng updates for Ubuntu 15.10 Wily Werewolf

An on-going background project of mine is to add various interesting system stress tests to stress-ng.  Over the past several months I've been looking at the ways to exercise various less used or obscure system calls just to add more kernel coverage to the tool.

• rlimit - generate tens of thousands of SIGXFSZ and many SIGXCPU signals
• itimer - exercise ITIMER_PROF and generate SIGPROF signals
• mlock - lock and unlock pages with mlock()/munlock()
• timerfd - exercise rapid CLOCK_REALTIME events by select() and read() on a timerfd.
• memfd - exercise anonymous populated page memory mapping and unmappoing using memfd.
• more aggressive affinity stressor changes to force more CPU IPIs
• hdd - add readv/writev I/O option
• tee - tee data between a writer and reader process using tee()
• crypt - encrypt data with MD5, SHA-256 and SHA-512 using libcrypt
• mmapmany - perform tens of thousands of memory maps/unmaps to exhaust the per-process mapping limit.
• zombie - fill up process table with tens of thousands of zombie processes
• str - heavily exercise a range of glibc string functions
• xattr - exercise file extended attributes
• readahead - random reads with readaheads
• vm - add a rowhammer memory stressor

..as well as extra per-stressor configuration settings and a lot of code clean up and bug fixing.

I've recently been using stress-ng to exercise various kernels on a range of hardware and it has been useful in forcing bugs, especially with the memory specific stressors that seem to trip low memory corner cases.

stress-ng 0.04.01 will be soon available in Ubuntu 15.10 Wily Werewolf.  Visit the stress-ng project page for more details.