[v3,0/3] Randomize memory access of dirty_log_perf_test

Message

Colton Lewis Sept. 1, 2022, 7:52 p.m. UTC

This patch adds the ability to randomize parts of dirty_log_perf_test,
specifically the order pages are accessed and whether pages are read
or written.

This version scraps the use of arrays to remove the memory management
concerns and implementes a well-known random number generator, the
Park-Miller Linear Congruential Generator, for the guest code to use
directly. From comments on v2, several others agree this is the right
approach. I came to the same conclusion and was already working on it.

Though I had this idea and ignored it previously over concerns about
introducing mysterious code, doing some research convinced me
Park-Miller is both extremely easy to understand and high enough
quality for this purpose. I also believe this approach better
preserves the integrity of the test as a couple math instructions are
definitely faster than fetching from memory.

Compiled and run on x86_64 and arm64 to test the new flags.
Based on v5.19 as tests on kvm/queue do not build

Colton Lewis (3):
  KVM: selftests: Implement random number generation for guest code.
  KVM: selftests: Randomize which pages are written vs read.
  KVM: selftests: Randomize page access order.

 .../selftests/kvm/access_tracking_perf_test.c |  2 +-
 .../selftests/kvm/dirty_log_perf_test.c       | 48 +++++++++++++------
 .../selftests/kvm/include/perf_test_util.h    |  8 +++-
 .../selftests/kvm/lib/perf_test_util.c        | 40 +++++++++++++---
 4 files changed, 74 insertions(+), 24 deletions(-)

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2.37.2.672.g94769d06f0-goog