| Message ID | 20221102160007.1279193-2-coltonlewis@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | randomize memory access of dirty_log_perf_test | expand |
On Wed, Nov 02, 2022, Colton Lewis wrote: > Implement random number generator for guest code to randomize parts > of the test, making it less predictable and a more accurate reflection > of reality. > > The random number generator chosen is the Park-Miller Linear > Congruential Generator, a fancy name for a basic and well-understood > random number generator entirely sufficient for this purpose. Each > vCPU calculates its own seed by adding its index to the seed provided. > > Signed-off-by: Colton Lewis <coltonlewis@google.com> > --- Reviewed-by: Sean Christopherson <seanjc@google.com>
On Wed, Nov 02, 2022 at 04:00:04PM +0000, Colton Lewis wrote: > Implement random number generator for guest code to randomize parts > of the test, making it less predictable and a more accurate reflection > of reality. > > The random number generator chosen is the Park-Miller Linear > Congruential Generator, a fancy name for a basic and well-understood > random number generator entirely sufficient for this purpose. Each > vCPU calculates its own seed by adding its index to the seed provided. Move this last sentence to patch 3? > > Signed-off-by: Colton Lewis <coltonlewis@google.com> Otherwise, Reviewed-by: David Matlack <dmatlack@google.com>
diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h index befc754ce9b3..9e4f36a1a8b0 100644 --- a/tools/testing/selftests/kvm/include/test_util.h +++ b/tools/testing/selftests/kvm/include/test_util.h @@ -152,4 +152,11 @@ static inline void *align_ptr_up(void *x, size_t size) return (void *)align_up((unsigned long)x, size); } +struct guest_random_state { + uint32_t seed; +}; + +struct guest_random_state new_guest_random_state(uint32_t seed); +uint32_t guest_random_u32(struct guest_random_state *state); + #endif /* SELFTEST_KVM_TEST_UTIL_H */ diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c index 6d23878bbfe1..c4d2749fb2c3 100644 --- a/tools/testing/selftests/kvm/lib/test_util.c +++ b/tools/testing/selftests/kvm/lib/test_util.c @@ -17,6 +17,23 @@ #include "test_util.h" +/* + * Random number generator that is usable from guest code. This is the + * Park-Miller LCG using standard constants. + */ + +struct guest_random_state new_guest_random_state(uint32_t seed) +{ + struct guest_random_state s = {.seed = seed}; + return s; +} + +uint32_t guest_random_u32(struct guest_random_state *state) +{ + state->seed = (uint64_t)state->seed * 48271 % ((uint32_t)(1 << 31) - 1); + return state->seed; +} + /* * Parses "[0-9]+[kmgt]?". */
Implement random number generator for guest code to randomize parts of the test, making it less predictable and a more accurate reflection of reality. The random number generator chosen is the Park-Miller Linear Congruential Generator, a fancy name for a basic and well-understood random number generator entirely sufficient for this purpose. Each vCPU calculates its own seed by adding its index to the seed provided. Signed-off-by: Colton Lewis <coltonlewis@google.com> --- tools/testing/selftests/kvm/include/test_util.h | 7 +++++++ tools/testing/selftests/kvm/lib/test_util.c | 17 +++++++++++++++++ 2 files changed, 24 insertions(+)