Wednesday, 29 June 2016

What's new in stress-ng 0.06.07?

Since my last blog post about stress-ng, I've pushed out several more small releases that incorporate new features and (as ever) a bunch more bug fixes.  I've been eyeballing gcov kernel coverage stats to find more regions in the kernel where stress-ng needs to exercise.   Also, testing on a range of hardware (arm64, s390x, etc) and a range of kernels has eeked out some bugs and helped me to improve stress-ng.  So what's new?

New stressors:
  • ioprio  - exercises ioprio_get(2) and ioprio_set(2) (I/O scheduling classes and priorities)
  • opcode - generates random object code and executes this, generating and catching illegal instructions, bus errors,  segmentation  faults,  traps and floating  point errors.
  • stackmmap - allocates a 2MB stack that is memory mapped onto a temporary file. A recursive function works down the stack and flushes dirty stack pages back to the memory mapped file using msync(2) until the end of the stack is reached (stack overflow). This exercises dirty page and stack exception handling.
  • madvise - applies random madvise(2) advise settings on pages of a 4MB file backed shared memory mapping.
  • pty - exercise pseudo terminal operations.
  • chown - trivial chown(2) file ownership exerciser.
  • seal - fcntl(2) file SEALing exerciser.
  • locka - POSIX advisory locking exerciser.
  • lockofd - fcntl(2) F_OFD_SETLK/GETLK open file description lock exerciser.
Improved stressors:
  • msg: add in IPC_INFO, MSG_INFO, MSG_STAT msgctl calls
  • vecmath: add more ops to make vecmath more demanding
  • socket: add --sock-type socket type option, e.g. stream or seqpacket
  • shm and shm-sysv: add msync'ing on the shm regions
  • memfd: add hole punching
  • mremap: add MAP_FIXED remappings
  • shm: sync, expand, shrink shm regions
  • dup: use dup2(2)
  • seek: add SEEK_CUR, SEEK_END seek options
  • utime: exercise UTIME_NOW and UTIME_OMIT settings
  • userfaultfd: add zero page handling
  • cache:  use cacheflush() on systems that provide this syscall
  • key:  add request_key system call
  • nice: add some randomness to the delay to unsync nicenesses changes
If any new features land in Linux 4.8 I may add stressors for them, but for now I suspect that's about it for the big changes for stress-ng for the Ubuntu Yakkey 16.10 release.

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