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[34.82.181.220]) by smtp.gmail.com with ESMTPSA id j5-20020a170902da8500b0016d7b2352desm14325479plx.244.2022.09.01.10.37.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 01 Sep 2022 10:37:16 -0700 (PDT) Date: Thu, 1 Sep 2022 10:37:12 -0700 From: Ricardo Koller To: Colton Lewis Cc: kvm@vger.kernel.org, pbonzini@redhat.com, maz@kernel.org, dmatlack@google.com, seanjc@google.com, oupton@google.com Subject: Re: [PATCH v2 1/3] KVM: selftests: Create source of randomness for guest code. Message-ID: References: <20220817214146.3285106-1-coltonlewis@google.com> <20220817214146.3285106-2-coltonlewis@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220817214146.3285106-2-coltonlewis@google.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, Aug 17, 2022 at 09:41:44PM +0000, Colton Lewis wrote: > Create for each vcpu an array of random numbers to be used as a source > of randomness when executing guest code. Randomness should be useful > for approaching more realistic conditions in dirty_log_perf_test. > > Create a -r argument to specify a random seed. If no argument > is provided, the seed defaults to the current Unix timestamp. > > The random arrays are allocated and filled as part of VM creation. The > additional memory used is one 32-bit number per guest VM page to > ensure one number for each iteration of the inner loop of guest_code. > > Signed-off-by: Colton Lewis > --- > .../selftests/kvm/dirty_log_perf_test.c | 11 ++++- > .../selftests/kvm/include/perf_test_util.h | 3 ++ > .../selftests/kvm/lib/perf_test_util.c | 45 ++++++++++++++++++- > 3 files changed, 55 insertions(+), 4 deletions(-) > > diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c > index f99e39a672d3..362b946019e9 100644 > --- a/tools/testing/selftests/kvm/dirty_log_perf_test.c > +++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c > @@ -132,6 +132,7 @@ struct test_params { > bool partition_vcpu_memory_access; > enum vm_mem_backing_src_type backing_src; > int slots; > + uint32_t random_seed; > }; > > static void toggle_dirty_logging(struct kvm_vm *vm, int slots, bool enable) > @@ -225,6 +226,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) > p->slots, p->backing_src, > p->partition_vcpu_memory_access); > > + perf_test_set_random_seed(vm, p->random_seed); > perf_test_set_wr_fract(vm, p->wr_fract); > > guest_num_pages = (nr_vcpus * guest_percpu_mem_size) >> vm->page_shift; > @@ -352,7 +354,7 @@ static void help(char *name) > { > puts(""); > printf("usage: %s [-h] [-i iterations] [-p offset] [-g] " > - "[-m mode] [-n] [-b vcpu bytes] [-v vcpus] [-o] [-s mem type]" > + "[-m mode] [-n] [-b vcpu bytes] [-v vcpus] [-o] [-r random seed ] [-s mem type]" > "[-x memslots]\n", name); > puts(""); > printf(" -i: specify iteration counts (default: %"PRIu64")\n", > @@ -380,6 +382,7 @@ static void help(char *name) > printf(" -v: specify the number of vCPUs to run.\n"); > printf(" -o: Overlap guest memory accesses instead of partitioning\n" > " them into a separate region of memory for each vCPU.\n"); > + printf(" -r: specify the starting random seed.\n"); > backing_src_help("-s"); > printf(" -x: Split the memory region into this number of memslots.\n" > " (default: 1)\n"); > @@ -396,6 +399,7 @@ int main(int argc, char *argv[]) > .partition_vcpu_memory_access = true, > .backing_src = DEFAULT_VM_MEM_SRC, > .slots = 1, > + .random_seed = time(NULL), > }; > int opt; > > @@ -406,7 +410,7 @@ int main(int argc, char *argv[]) > > guest_modes_append_default(); > > - while ((opt = getopt(argc, argv, "eghi:p:m:nb:f:v:os:x:")) != -1) { > + while ((opt = getopt(argc, argv, "eghi:p:m:nb:f:v:or:s:x:")) != -1) { > switch (opt) { > case 'e': > /* 'e' is for evil. */ > @@ -442,6 +446,9 @@ int main(int argc, char *argv[]) > case 'o': > p.partition_vcpu_memory_access = false; > break; > + case 'r': > + p.random_seed = atoi(optarg); > + break; > case 's': > p.backing_src = parse_backing_src_type(optarg); > break; > diff --git a/tools/testing/selftests/kvm/include/perf_test_util.h b/tools/testing/selftests/kvm/include/perf_test_util.h > index eaa88df0555a..9517956424fc 100644 > --- a/tools/testing/selftests/kvm/include/perf_test_util.h > +++ b/tools/testing/selftests/kvm/include/perf_test_util.h > @@ -23,6 +23,7 @@ struct perf_test_vcpu_args { > uint64_t gpa; > uint64_t gva; > uint64_t pages; > + vm_vaddr_t random_array; > > /* Only used by the host userspace part of the vCPU thread */ > struct kvm_vcpu *vcpu; > @@ -35,6 +36,7 @@ struct perf_test_args { > uint64_t gpa; > uint64_t size; > uint64_t guest_page_size; > + uint32_t random_seed; > int wr_fract; > > /* Run vCPUs in L2 instead of L1, if the architecture supports it. */ > @@ -52,6 +54,7 @@ struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int nr_vcpus, > void perf_test_destroy_vm(struct kvm_vm *vm); > > void perf_test_set_wr_fract(struct kvm_vm *vm, int wr_fract); > +void perf_test_set_random_seed(struct kvm_vm *vm, uint32_t random_seed); > > 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 9618b37c66f7..8d85923acb4e 100644 > --- a/tools/testing/selftests/kvm/lib/perf_test_util.c > +++ b/tools/testing/selftests/kvm/lib/perf_test_util.c > @@ -70,6 +70,35 @@ void perf_test_guest_code(uint32_t vcpu_idx) > } > } > > +void perf_test_alloc_random_arrays(uint32_t nr_vcpus, uint32_t nr_randoms) > +{ > + struct perf_test_args *pta = &perf_test_args; > + > + for (uint32_t i = 0; i < nr_vcpus; i++) { > + pta->vcpu_args[i].random_array = vm_vaddr_alloc( > + pta->vm, > + nr_randoms * sizeof(uint32_t), > + KVM_UTIL_MIN_VADDR); > + pr_debug("Random row %d vaddr: %p.\n", i, (void *)pta->vcpu_args[i].random_array); > + } > +} > + > +void perf_test_fill_random_arrays(uint32_t nr_vcpus, uint32_t nr_randoms) > +{ > + struct perf_test_args *pta = &perf_test_args; > + uint32_t *host_row; > + > + for (uint32_t i = 0; i < nr_vcpus; i++) { > + host_row = addr_gva2hva(pta->vm, pta->vcpu_args[i].random_array); > + > + for (uint32_t j = 0; j < nr_randoms; j++) > + host_row[j] = random(); > + > + pr_debug("New randoms row %d: %d, %d, %d...\n", > + i, host_row[0], host_row[1], host_row[2]); > + } > +} > + > void perf_test_setup_vcpus(struct kvm_vm *vm, int nr_vcpus, > struct kvm_vcpu *vcpus[], > uint64_t vcpu_memory_bytes, > @@ -120,8 +149,9 @@ struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int nr_vcpus, > > pr_info("Testing guest mode: %s\n", vm_guest_mode_string(mode)); > > - /* By default vCPUs will write to memory. */ > - pta->wr_fract = 1; > + /* Set perf_test_args defaults. */ > + pta->wr_fract = 100; This is not needed in this commit. It's changing the behavior at the current commit, as it's now defaulting to 0% reads (using the current check in guest_code()). > + pta->random_seed = time(NULL); > > /* > * Snapshot the non-huge page size. This is used by the guest code to > @@ -211,6 +241,11 @@ struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int nr_vcpus, > > ucall_init(vm, NULL); > > + srandom(perf_test_args.random_seed); > + pr_info("Random seed: %d\n", perf_test_args.random_seed); > + perf_test_alloc_random_arrays(nr_vcpus, vcpu_memory_bytes >> vm->page_shift); > + perf_test_fill_random_arrays(nr_vcpus, vcpu_memory_bytes >> vm->page_shift); > + > /* Export the shared variables to the guest. */ > sync_global_to_guest(vm, perf_test_args); > > @@ -229,6 +264,12 @@ void perf_test_set_wr_fract(struct kvm_vm *vm, int wr_fract) > sync_global_to_guest(vm, perf_test_args); > } > > +void perf_test_set_random_seed(struct kvm_vm *vm, uint32_t random_seed) > +{ > + perf_test_args.random_seed = random_seed; > + sync_global_to_guest(vm, perf_test_args); > +} > + > uint64_t __weak perf_test_nested_pages(int nr_vcpus) > { > return 0; > -- > 2.37.1.595.g718a3a8f04-goog >