| Message ID | 20220909124300.3409187-4-coltonlewis@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: selftests: randomize memory access of dirty_log_perf_test | expand |
On Fri, Sep 09, 2022 at 12:43:00PM +0000, Colton Lewis wrote: > Create the ability to randomize page access order with the -a > argument, including the possibility that the same pages may be hit > multiple times during an iteration or not at all. > > Population sets random access to false. > Reviewed-by: Ricardo Koller <ricarkol@google.com> > Signed-off-by: Colton Lewis <coltonlewis@google.com> > --- > tools/testing/selftests/kvm/dirty_log_perf_test.c | 11 +++++++++-- > .../selftests/kvm/include/perf_test_util.h | 2 ++ > tools/testing/selftests/kvm/lib/perf_test_util.c | 15 ++++++++++++++- > 3 files changed, 25 insertions(+), 3 deletions(-) > > diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c > index c2ad299b3760..3639d5f95033 100644 > --- a/tools/testing/selftests/kvm/dirty_log_perf_test.c > +++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c > @@ -127,6 +127,7 @@ struct test_params { > int slots; > uint32_t write_percent; > uint32_t random_seed; > + bool random_access; > }; > > static void toggle_dirty_logging(struct kvm_vm *vm, int slots, bool enable) > @@ -248,6 +249,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) > vcpu_last_completed_iteration[vcpu_id] = -1; > > perf_test_set_write_percent(vm, 100); > + perf_test_set_random_access(vm, false); > perf_test_start_vcpu_threads(nr_vcpus, vcpu_worker); > > /* Allow the vCPUs to populate memory */ > @@ -270,6 +272,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) > ts_diff.tv_sec, ts_diff.tv_nsec); > > perf_test_set_write_percent(vm, p->write_percent); > + perf_test_set_random_access(vm, p->random_access); > > while (iteration < p->iterations) { > /* > @@ -341,10 +344,11 @@ static void run_test(enum vm_guest_mode mode, void *arg) > static void help(char *name) > { > puts(""); > - printf("usage: %s [-h] [-i iterations] [-p offset] [-g] " > + printf("usage: %s [-h] [-a] [-i iterations] [-p offset] [-g] " > "[-m mode] [-n] [-b vcpu bytes] [-v vcpus] [-o] [-r random seed ] [-s mem type]" > "[-x memslots] [-w percentage]\n", name); > puts(""); > + printf(" -a: access memory randomly rather than in order.\n"); > printf(" -i: specify iteration counts (default: %"PRIu64")\n", > TEST_HOST_LOOP_N); > printf(" -g: Do not enable KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2. This\n" > @@ -396,8 +400,11 @@ int main(int argc, char *argv[]) > > guest_modes_append_default(); > > - while ((opt = getopt(argc, argv, "ghi:p:m:nb:v:or:s:x:w:")) != -1) { > + while ((opt = getopt(argc, argv, "aghi:p:m:nb:v:or:s:x:w:")) != -1) { > switch (opt) { > + case 'a': > + p.random_access = true; > + break; > case 'g': > dirty_log_manual_caps = 0; > break; > diff --git a/tools/testing/selftests/kvm/include/perf_test_util.h b/tools/testing/selftests/kvm/include/perf_test_util.h > index f93f2ea7c6a3..d9664a31e01c 100644 > --- a/tools/testing/selftests/kvm/include/perf_test_util.h > +++ b/tools/testing/selftests/kvm/include/perf_test_util.h > @@ -39,6 +39,7 @@ struct perf_test_args { > > /* Run vCPUs in L2 instead of L1, if the architecture supports it. */ > bool nested; > + bool random_access; > > struct perf_test_vcpu_args vcpu_args[KVM_MAX_VCPUS]; > }; > @@ -53,6 +54,7 @@ void perf_test_destroy_vm(struct kvm_vm *vm); > > void perf_test_set_write_percent(struct kvm_vm *vm, uint32_t write_percent); > void perf_test_set_random_seed(struct kvm_vm *vm, uint32_t random_seed); > +void perf_test_set_random_access(struct kvm_vm *vm, bool random_access); > > void perf_test_start_vcpu_threads(int vcpus, void (*vcpu_fn)(struct perf_test_vcpu_args *)); > void perf_test_join_vcpu_threads(int vcpus); > diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c > index 12a3597be1f9..ce657fa92f05 100644 > --- a/tools/testing/selftests/kvm/lib/perf_test_util.c > +++ b/tools/testing/selftests/kvm/lib/perf_test_util.c > @@ -46,6 +46,7 @@ void perf_test_guest_code(uint32_t vcpu_id) > struct perf_test_vcpu_args *vcpu_args = &pta->vcpu_args[vcpu_id]; > uint64_t gva; > uint64_t pages; > + uint64_t addr; > int i; > uint32_t rand = pta->random_seed + vcpu_id; > > @@ -57,7 +58,13 @@ void perf_test_guest_code(uint32_t vcpu_id) > > while (true) { > for (i = 0; i < pages; i++) { > - uint64_t addr = gva + (i * pta->guest_page_size); > + guest_random(&rand); > + > + if (pta->random_access) > + addr = gva + ((rand % pages) * pta->guest_page_size); > + else > + addr = gva + (i * pta->guest_page_size); > + > guest_random(&rand); > > if (rand % 100 < pta->write_percent) > @@ -233,6 +240,12 @@ void perf_test_set_random_seed(struct kvm_vm *vm, uint32_t random_seed) > sync_global_to_guest(vm, perf_test_args.random_seed); > } > > +void perf_test_set_random_access(struct kvm_vm *vm, bool random_access) > +{ > + perf_test_args.random_access = random_access; > + sync_global_to_guest(vm, perf_test_args.random_access); > +} > + > uint64_t __weak perf_test_nested_pages(int nr_vcpus) > { > return 0; > -- > 2.37.2.789.g6183377224-goog >
On Fri, Sep 09, 2022 at 12:43:00PM +0000, Colton Lewis wrote: > Create the ability to randomize page access order with the -a > argument, including the possibility that the same pages may be hit > multiple times during an iteration or not at all. > > Population sets random access to false. Please make sure to also explain the why in addition to the what. > > Signed-off-by: Colton Lewis <coltonlewis@google.com> > --- > tools/testing/selftests/kvm/dirty_log_perf_test.c | 11 +++++++++-- > .../selftests/kvm/include/perf_test_util.h | 2 ++ > tools/testing/selftests/kvm/lib/perf_test_util.c | 15 ++++++++++++++- > 3 files changed, 25 insertions(+), 3 deletions(-) > > diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c > index c2ad299b3760..3639d5f95033 100644 > --- a/tools/testing/selftests/kvm/dirty_log_perf_test.c > +++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c > @@ -127,6 +127,7 @@ struct test_params { > int slots; > uint32_t write_percent; > uint32_t random_seed; > + bool random_access; > }; > > static void toggle_dirty_logging(struct kvm_vm *vm, int slots, bool enable) > @@ -248,6 +249,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) > vcpu_last_completed_iteration[vcpu_id] = -1; > > perf_test_set_write_percent(vm, 100); > + perf_test_set_random_access(vm, false); > perf_test_start_vcpu_threads(nr_vcpus, vcpu_worker); > > /* Allow the vCPUs to populate memory */ > @@ -270,6 +272,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) > ts_diff.tv_sec, ts_diff.tv_nsec); > > perf_test_set_write_percent(vm, p->write_percent); > + perf_test_set_random_access(vm, p->random_access); > > while (iteration < p->iterations) { > /* > @@ -341,10 +344,11 @@ static void run_test(enum vm_guest_mode mode, void *arg) > static void help(char *name) > { > puts(""); > - printf("usage: %s [-h] [-i iterations] [-p offset] [-g] " > + printf("usage: %s [-h] [-a] [-i iterations] [-p offset] [-g] " > "[-m mode] [-n] [-b vcpu bytes] [-v vcpus] [-o] [-r random seed ] [-s mem type]" > "[-x memslots] [-w percentage]\n", name); > puts(""); > + printf(" -a: access memory randomly rather than in order.\n"); > printf(" -i: specify iteration counts (default: %"PRIu64")\n", > TEST_HOST_LOOP_N); > printf(" -g: Do not enable KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2. This\n" > @@ -396,8 +400,11 @@ int main(int argc, char *argv[]) > > guest_modes_append_default(); > > - while ((opt = getopt(argc, argv, "ghi:p:m:nb:v:or:s:x:w:")) != -1) { > + while ((opt = getopt(argc, argv, "aghi:p:m:nb:v:or:s:x:w:")) != -1) { > switch (opt) { > + case 'a': > + p.random_access = true; > + break; > case 'g': > dirty_log_manual_caps = 0; > break; > diff --git a/tools/testing/selftests/kvm/include/perf_test_util.h b/tools/testing/selftests/kvm/include/perf_test_util.h > index f93f2ea7c6a3..d9664a31e01c 100644 > --- a/tools/testing/selftests/kvm/include/perf_test_util.h > +++ b/tools/testing/selftests/kvm/include/perf_test_util.h > @@ -39,6 +39,7 @@ struct perf_test_args { > > /* Run vCPUs in L2 instead of L1, if the architecture supports it. */ > bool nested; > + bool random_access; > > struct perf_test_vcpu_args vcpu_args[KVM_MAX_VCPUS]; > }; > @@ -53,6 +54,7 @@ void perf_test_destroy_vm(struct kvm_vm *vm); > > void perf_test_set_write_percent(struct kvm_vm *vm, uint32_t write_percent); > void perf_test_set_random_seed(struct kvm_vm *vm, uint32_t random_seed); > +void perf_test_set_random_access(struct kvm_vm *vm, bool random_access); > > void perf_test_start_vcpu_threads(int vcpus, void (*vcpu_fn)(struct perf_test_vcpu_args *)); > void perf_test_join_vcpu_threads(int vcpus); > diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c > index 12a3597be1f9..ce657fa92f05 100644 > --- a/tools/testing/selftests/kvm/lib/perf_test_util.c > +++ b/tools/testing/selftests/kvm/lib/perf_test_util.c > @@ -46,6 +46,7 @@ void perf_test_guest_code(uint32_t vcpu_id) > struct perf_test_vcpu_args *vcpu_args = &pta->vcpu_args[vcpu_id]; > uint64_t gva; > uint64_t pages; > + uint64_t addr; > int i; > uint32_t rand = pta->random_seed + vcpu_id; > > @@ -57,7 +58,13 @@ void perf_test_guest_code(uint32_t vcpu_id) > > while (true) { > for (i = 0; i < pages; i++) { > - uint64_t addr = gva + (i * pta->guest_page_size); > + guest_random(&rand); > + > + if (pta->random_access) > + addr = gva + ((rand % pages) * pta->guest_page_size); > + else > + addr = gva + (i * pta->guest_page_size); > + > guest_random(&rand); Is it on purpose use a separate random number for access offset and read/write? > > if (rand % 100 < pta->write_percent) > @@ -233,6 +240,12 @@ void perf_test_set_random_seed(struct kvm_vm *vm, uint32_t random_seed) > sync_global_to_guest(vm, perf_test_args.random_seed); > } > > +void perf_test_set_random_access(struct kvm_vm *vm, bool random_access) > +{ > + perf_test_args.random_access = random_access; > + sync_global_to_guest(vm, perf_test_args.random_access); > +} > + > uint64_t __weak perf_test_nested_pages(int nr_vcpus) > { > return 0; > -- > 2.37.2.789.g6183377224-goog >
On Fri, Sep 09, 2022 at 10:26:10AM -0700, David Matlack wrote: > On Fri, Sep 09, 2022 at 12:43:00PM +0000, Colton Lewis wrote: > > Create the ability to randomize page access order with the -a > > argument, including the possibility that the same pages may be hit > > multiple times during an iteration or not at all. > > > > Population sets random access to false. > > Please make sure to also explain the why in addition to the what. > > > > > Signed-off-by: Colton Lewis <coltonlewis@google.com> > > --- > > tools/testing/selftests/kvm/dirty_log_perf_test.c | 11 +++++++++-- > > .../selftests/kvm/include/perf_test_util.h | 2 ++ > > tools/testing/selftests/kvm/lib/perf_test_util.c | 15 ++++++++++++++- > > 3 files changed, 25 insertions(+), 3 deletions(-) > > > > diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c > > index c2ad299b3760..3639d5f95033 100644 > > --- a/tools/testing/selftests/kvm/dirty_log_perf_test.c > > +++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c > > @@ -127,6 +127,7 @@ struct test_params { > > int slots; > > uint32_t write_percent; > > uint32_t random_seed; > > + bool random_access; > > }; > > > > static void toggle_dirty_logging(struct kvm_vm *vm, int slots, bool enable) > > @@ -248,6 +249,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) > > vcpu_last_completed_iteration[vcpu_id] = -1; > > > > perf_test_set_write_percent(vm, 100); > > + perf_test_set_random_access(vm, false); > > perf_test_start_vcpu_threads(nr_vcpus, vcpu_worker); > > > > /* Allow the vCPUs to populate memory */ > > @@ -270,6 +272,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) > > ts_diff.tv_sec, ts_diff.tv_nsec); > > > > perf_test_set_write_percent(vm, p->write_percent); > > + perf_test_set_random_access(vm, p->random_access); > > > > while (iteration < p->iterations) { > > /* > > @@ -341,10 +344,11 @@ static void run_test(enum vm_guest_mode mode, void *arg) > > static void help(char *name) > > { > > puts(""); > > - printf("usage: %s [-h] [-i iterations] [-p offset] [-g] " > > + printf("usage: %s [-h] [-a] [-i iterations] [-p offset] [-g] " > > "[-m mode] [-n] [-b vcpu bytes] [-v vcpus] [-o] [-r random seed ] [-s mem type]" > > "[-x memslots] [-w percentage]\n", name); > > puts(""); > > + printf(" -a: access memory randomly rather than in order.\n"); > > printf(" -i: specify iteration counts (default: %"PRIu64")\n", > > TEST_HOST_LOOP_N); > > printf(" -g: Do not enable KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2. This\n" > > @@ -396,8 +400,11 @@ int main(int argc, char *argv[]) > > > > guest_modes_append_default(); > > > > - while ((opt = getopt(argc, argv, "ghi:p:m:nb:v:or:s:x:w:")) != -1) { > > + while ((opt = getopt(argc, argv, "aghi:p:m:nb:v:or:s:x:w:")) != -1) { > > switch (opt) { > > + case 'a': > > + p.random_access = true; > > + break; > > case 'g': > > dirty_log_manual_caps = 0; > > break; > > diff --git a/tools/testing/selftests/kvm/include/perf_test_util.h b/tools/testing/selftests/kvm/include/perf_test_util.h > > index f93f2ea7c6a3..d9664a31e01c 100644 > > --- a/tools/testing/selftests/kvm/include/perf_test_util.h > > +++ b/tools/testing/selftests/kvm/include/perf_test_util.h > > @@ -39,6 +39,7 @@ struct perf_test_args { > > > > /* Run vCPUs in L2 instead of L1, if the architecture supports it. */ > > bool nested; > > + bool random_access; > > > > struct perf_test_vcpu_args vcpu_args[KVM_MAX_VCPUS]; > > }; > > @@ -53,6 +54,7 @@ void perf_test_destroy_vm(struct kvm_vm *vm); > > > > void perf_test_set_write_percent(struct kvm_vm *vm, uint32_t write_percent); > > void perf_test_set_random_seed(struct kvm_vm *vm, uint32_t random_seed); > > +void perf_test_set_random_access(struct kvm_vm *vm, bool random_access); > > > > void perf_test_start_vcpu_threads(int vcpus, void (*vcpu_fn)(struct perf_test_vcpu_args *)); > > void perf_test_join_vcpu_threads(int vcpus); > > diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c > > index 12a3597be1f9..ce657fa92f05 100644 > > --- a/tools/testing/selftests/kvm/lib/perf_test_util.c > > +++ b/tools/testing/selftests/kvm/lib/perf_test_util.c > > @@ -46,6 +46,7 @@ void perf_test_guest_code(uint32_t vcpu_id) > > struct perf_test_vcpu_args *vcpu_args = &pta->vcpu_args[vcpu_id]; > > uint64_t gva; > > uint64_t pages; > > + uint64_t addr; > > int i; > > uint32_t rand = pta->random_seed + vcpu_id; > > > > @@ -57,7 +58,13 @@ void perf_test_guest_code(uint32_t vcpu_id) > > > > while (true) { > > for (i = 0; i < pages; i++) { > > - uint64_t addr = gva + (i * pta->guest_page_size); > > + guest_random(&rand); > > + > > + if (pta->random_access) > > + addr = gva + ((rand % pages) * pta->guest_page_size); > > + else > > + addr = gva + (i * pta->guest_page_size); > > + > > guest_random(&rand); > > Is it on purpose use a separate random number for access offset and > read/write? > It's because of the following, from https://lore.kernel.org/kvm/YxDvVyFpMC9U3O25@google.com/ I think addr and write_percent need two different random numbers. Otherwise, you will end up with a situation where all addresses where (rnd_arr[i] % 100 < pta->write_percent) will get a write (always). Something like this: 012345678 <= address wwwrrrwww 837561249 <= access order I think the best way to fix this is to abstract the random number reading into something like get_next_rand(), and use it twice per iteration. > > > > if (rand % 100 < pta->write_percent) > > @@ -233,6 +240,12 @@ void perf_test_set_random_seed(struct kvm_vm *vm, uint32_t random_seed) > > sync_global_to_guest(vm, perf_test_args.random_seed); > > } > > > > +void perf_test_set_random_access(struct kvm_vm *vm, bool random_access) > > +{ > > + perf_test_args.random_access = random_access; > > + sync_global_to_guest(vm, perf_test_args.random_access); > > +} > > + > > uint64_t __weak perf_test_nested_pages(int nr_vcpus) > > { > > return 0; > > -- > > 2.37.2.789.g6183377224-goog > >
On Fri, Sep 9, 2022 at 10:31 AM Ricardo Koller <ricarkol@google.com> wrote: > > On Fri, Sep 09, 2022 at 10:26:10AM -0700, David Matlack wrote: > > On Fri, Sep 09, 2022 at 12:43:00PM +0000, Colton Lewis wrote: > > > Create the ability to randomize page access order with the -a > > > argument, including the possibility that the same pages may be hit > > > multiple times during an iteration or not at all. > > > > > > Population sets random access to false. > > > > Please make sure to also explain the why in addition to the what. > > > > > > > > Signed-off-by: Colton Lewis <coltonlewis@google.com> > > > --- > > > tools/testing/selftests/kvm/dirty_log_perf_test.c | 11 +++++++++-- > > > .../selftests/kvm/include/perf_test_util.h | 2 ++ > > > tools/testing/selftests/kvm/lib/perf_test_util.c | 15 ++++++++++++++- > > > 3 files changed, 25 insertions(+), 3 deletions(-) > > > > > > diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c > > > index c2ad299b3760..3639d5f95033 100644 > > > --- a/tools/testing/selftests/kvm/dirty_log_perf_test.c > > > +++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c > > > @@ -127,6 +127,7 @@ struct test_params { > > > int slots; > > > uint32_t write_percent; > > > uint32_t random_seed; > > > + bool random_access; > > > }; > > > > > > static void toggle_dirty_logging(struct kvm_vm *vm, int slots, bool enable) > > > @@ -248,6 +249,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) > > > vcpu_last_completed_iteration[vcpu_id] = -1; > > > > > > perf_test_set_write_percent(vm, 100); > > > + perf_test_set_random_access(vm, false); > > > perf_test_start_vcpu_threads(nr_vcpus, vcpu_worker); > > > > > > /* Allow the vCPUs to populate memory */ > > > @@ -270,6 +272,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) > > > ts_diff.tv_sec, ts_diff.tv_nsec); > > > > > > perf_test_set_write_percent(vm, p->write_percent); > > > + perf_test_set_random_access(vm, p->random_access); > > > > > > while (iteration < p->iterations) { > > > /* > > > @@ -341,10 +344,11 @@ static void run_test(enum vm_guest_mode mode, void *arg) > > > static void help(char *name) > > > { > > > puts(""); > > > - printf("usage: %s [-h] [-i iterations] [-p offset] [-g] " > > > + printf("usage: %s [-h] [-a] [-i iterations] [-p offset] [-g] " > > > "[-m mode] [-n] [-b vcpu bytes] [-v vcpus] [-o] [-r random seed ] [-s mem type]" > > > "[-x memslots] [-w percentage]\n", name); > > > puts(""); > > > + printf(" -a: access memory randomly rather than in order.\n"); > > > printf(" -i: specify iteration counts (default: %"PRIu64")\n", > > > TEST_HOST_LOOP_N); > > > printf(" -g: Do not enable KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2. This\n" > > > @@ -396,8 +400,11 @@ int main(int argc, char *argv[]) > > > > > > guest_modes_append_default(); > > > > > > - while ((opt = getopt(argc, argv, "ghi:p:m:nb:v:or:s:x:w:")) != -1) { > > > + while ((opt = getopt(argc, argv, "aghi:p:m:nb:v:or:s:x:w:")) != -1) { > > > switch (opt) { > > > + case 'a': > > > + p.random_access = true; > > > + break; > > > case 'g': > > > dirty_log_manual_caps = 0; > > > break; > > > diff --git a/tools/testing/selftests/kvm/include/perf_test_util.h b/tools/testing/selftests/kvm/include/perf_test_util.h > > > index f93f2ea7c6a3..d9664a31e01c 100644 > > > --- a/tools/testing/selftests/kvm/include/perf_test_util.h > > > +++ b/tools/testing/selftests/kvm/include/perf_test_util.h > > > @@ -39,6 +39,7 @@ struct perf_test_args { > > > > > > /* Run vCPUs in L2 instead of L1, if the architecture supports it. */ > > > bool nested; > > > + bool random_access; > > > > > > struct perf_test_vcpu_args vcpu_args[KVM_MAX_VCPUS]; > > > }; > > > @@ -53,6 +54,7 @@ void perf_test_destroy_vm(struct kvm_vm *vm); > > > > > > void perf_test_set_write_percent(struct kvm_vm *vm, uint32_t write_percent); > > > void perf_test_set_random_seed(struct kvm_vm *vm, uint32_t random_seed); > > > +void perf_test_set_random_access(struct kvm_vm *vm, bool random_access); > > > > > > void perf_test_start_vcpu_threads(int vcpus, void (*vcpu_fn)(struct perf_test_vcpu_args *)); > > > void perf_test_join_vcpu_threads(int vcpus); > > > diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c > > > index 12a3597be1f9..ce657fa92f05 100644 > > > --- a/tools/testing/selftests/kvm/lib/perf_test_util.c > > > +++ b/tools/testing/selftests/kvm/lib/perf_test_util.c > > > @@ -46,6 +46,7 @@ void perf_test_guest_code(uint32_t vcpu_id) > > > struct perf_test_vcpu_args *vcpu_args = &pta->vcpu_args[vcpu_id]; > > > uint64_t gva; > > > uint64_t pages; > > > + uint64_t addr; > > > int i; > > > uint32_t rand = pta->random_seed + vcpu_id; > > > > > > @@ -57,7 +58,13 @@ void perf_test_guest_code(uint32_t vcpu_id) > > > > > > while (true) { > > > for (i = 0; i < pages; i++) { > > > - uint64_t addr = gva + (i * pta->guest_page_size); > > > + guest_random(&rand); > > > + > > > + if (pta->random_access) > > > + addr = gva + ((rand % pages) * pta->guest_page_size); > > > + else > > > + addr = gva + (i * pta->guest_page_size); > > > + > > > guest_random(&rand); > > > > Is it on purpose use a separate random number for access offset and > > read/write? > > > > It's because of the following, from https://lore.kernel.org/kvm/YxDvVyFpMC9U3O25@google.com/ > > I think addr and write_percent need two different random numbers. > Otherwise, you will end up with a situation where all addresses where > (rnd_arr[i] % 100 < pta->write_percent) will get a write (always). > Something like this: > > 012345678 <= address > wwwrrrwww > 837561249 <= access order > > I think the best way to fix this is to abstract the random number > reading into something like get_next_rand(), and use it twice per > iteration. Makes sense. Depending on how many bits of randomness we need (e.g. read/write only needs 7) we could still use one random number. But the bit manipulation would probably more complex than just generating another random number (which looks like a fairly cheap calculation). Colton can you add a comment here to explain the subtlety? > > > > > > > if (rand % 100 < pta->write_percent) > > > @@ -233,6 +240,12 @@ void perf_test_set_random_seed(struct kvm_vm *vm, uint32_t random_seed) > > > sync_global_to_guest(vm, perf_test_args.random_seed); > > > } > > > > > > +void perf_test_set_random_access(struct kvm_vm *vm, bool random_access) > > > +{ > > > + perf_test_args.random_access = random_access; > > > + sync_global_to_guest(vm, perf_test_args.random_access); > > > +} > > > + > > > uint64_t __weak perf_test_nested_pages(int nr_vcpus) > > > { > > > return 0; > > > -- > > > 2.37.2.789.g6183377224-goog > > >
diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c index c2ad299b3760..3639d5f95033 100644 --- a/tools/testing/selftests/kvm/dirty_log_perf_test.c +++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c @@ -127,6 +127,7 @@ struct test_params { int slots; uint32_t write_percent; uint32_t random_seed; + bool random_access; }; static void toggle_dirty_logging(struct kvm_vm *vm, int slots, bool enable) @@ -248,6 +249,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) vcpu_last_completed_iteration[vcpu_id] = -1; perf_test_set_write_percent(vm, 100); + perf_test_set_random_access(vm, false); perf_test_start_vcpu_threads(nr_vcpus, vcpu_worker); /* Allow the vCPUs to populate memory */ @@ -270,6 +272,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) ts_diff.tv_sec, ts_diff.tv_nsec); perf_test_set_write_percent(vm, p->write_percent); + perf_test_set_random_access(vm, p->random_access); while (iteration < p->iterations) { /* @@ -341,10 +344,11 @@ static void run_test(enum vm_guest_mode mode, void *arg) static void help(char *name) { puts(""); - printf("usage: %s [-h] [-i iterations] [-p offset] [-g] " + printf("usage: %s [-h] [-a] [-i iterations] [-p offset] [-g] " "[-m mode] [-n] [-b vcpu bytes] [-v vcpus] [-o] [-r random seed ] [-s mem type]" "[-x memslots] [-w percentage]\n", name); puts(""); + printf(" -a: access memory randomly rather than in order.\n"); printf(" -i: specify iteration counts (default: %"PRIu64")\n", TEST_HOST_LOOP_N); printf(" -g: Do not enable KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2. This\n" @@ -396,8 +400,11 @@ int main(int argc, char *argv[]) guest_modes_append_default(); - while ((opt = getopt(argc, argv, "ghi:p:m:nb:v:or:s:x:w:")) != -1) { + while ((opt = getopt(argc, argv, "aghi:p:m:nb:v:or:s:x:w:")) != -1) { switch (opt) { + case 'a': + p.random_access = true; + break; case 'g': dirty_log_manual_caps = 0; break; diff --git a/tools/testing/selftests/kvm/include/perf_test_util.h b/tools/testing/selftests/kvm/include/perf_test_util.h index f93f2ea7c6a3..d9664a31e01c 100644 --- a/tools/testing/selftests/kvm/include/perf_test_util.h +++ b/tools/testing/selftests/kvm/include/perf_test_util.h @@ -39,6 +39,7 @@ struct perf_test_args { /* Run vCPUs in L2 instead of L1, if the architecture supports it. */ bool nested; + bool random_access; struct perf_test_vcpu_args vcpu_args[KVM_MAX_VCPUS]; }; @@ -53,6 +54,7 @@ void perf_test_destroy_vm(struct kvm_vm *vm); void perf_test_set_write_percent(struct kvm_vm *vm, uint32_t write_percent); void perf_test_set_random_seed(struct kvm_vm *vm, uint32_t random_seed); +void perf_test_set_random_access(struct kvm_vm *vm, bool random_access); void perf_test_start_vcpu_threads(int vcpus, void (*vcpu_fn)(struct perf_test_vcpu_args *)); void perf_test_join_vcpu_threads(int vcpus); diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c index 12a3597be1f9..ce657fa92f05 100644 --- a/tools/testing/selftests/kvm/lib/perf_test_util.c +++ b/tools/testing/selftests/kvm/lib/perf_test_util.c @@ -46,6 +46,7 @@ void perf_test_guest_code(uint32_t vcpu_id) struct perf_test_vcpu_args *vcpu_args = &pta->vcpu_args[vcpu_id]; uint64_t gva; uint64_t pages; + uint64_t addr; int i; uint32_t rand = pta->random_seed + vcpu_id; @@ -57,7 +58,13 @@ void perf_test_guest_code(uint32_t vcpu_id) while (true) { for (i = 0; i < pages; i++) { - uint64_t addr = gva + (i * pta->guest_page_size); + guest_random(&rand); + + if (pta->random_access) + addr = gva + ((rand % pages) * pta->guest_page_size); + else + addr = gva + (i * pta->guest_page_size); + guest_random(&rand); if (rand % 100 < pta->write_percent) @@ -233,6 +240,12 @@ void perf_test_set_random_seed(struct kvm_vm *vm, uint32_t random_seed) sync_global_to_guest(vm, perf_test_args.random_seed); } +void perf_test_set_random_access(struct kvm_vm *vm, bool random_access) +{ + perf_test_args.random_access = random_access; + sync_global_to_guest(vm, perf_test_args.random_access); +} + uint64_t __weak perf_test_nested_pages(int nr_vcpus) { return 0;
Create the ability to randomize page access order with the -a argument, including the possibility that the same pages may be hit multiple times during an iteration or not at all. Population sets random access to false. Signed-off-by: Colton Lewis <coltonlewis@google.com> --- tools/testing/selftests/kvm/dirty_log_perf_test.c | 11 +++++++++-- .../selftests/kvm/include/perf_test_util.h | 2 ++ tools/testing/selftests/kvm/lib/perf_test_util.c | 15 ++++++++++++++- 3 files changed, 25 insertions(+), 3 deletions(-)