From a69170c65acdf430e24fc1b6174dcc3aa501fe2f Mon Sep 17 00:00:00 2001 From: Gavin Shan Date: Thu, 20 Oct 2022 15:12:09 +0800 Subject: [PATCH] KVM: selftests: memslot_perf_test: Report optimal memory slots The memory area in each slot should be aligned to host page size. Otherwise, the test will fail. For example, the following command fails with the following messages with 64KB-page-size-host and 4KB-pae-size-guest. It's not user friendly to abort the test. Lets do something to report the optimal memory slots, instead of failing the test. # ./memslot_perf_test -v -s 1000 Number of memory slots: 999 Testing map performance with 1 runs, 5 seconds each Adding slots 1..999, each slot with 8 pages + 216 extra pages last ==== Test Assertion Failure ==== lib/kvm_util.c:824: vm_adjust_num_guest_pages(vm->mode, npages) == npages pid=19872 tid=19872 errno=0 - Success 1 0x00000000004065b3: vm_userspace_mem_region_add at kvm_util.c:822 2 0x0000000000401d6b: prepare_vm at memslot_perf_test.c:273 3 (inlined by) test_execute at memslot_perf_test.c:756 4 (inlined by) test_loop at memslot_perf_test.c:994 5 (inlined by) main at memslot_perf_test.c:1073 6 0x0000ffff7ebb4383: ?? ??:0 7 0x00000000004021ff: _start at :? Number of guest pages is not compatible with the host. Try npages=16 Report the optimal memory slots instead of failing the test when the memory area in each slot isn't aligned to host page size. With this applied, the optimal memory slots is reported. # ./memslot_perf_test -v -s 1000 Number of memory slots: 999 Testing map performance with 1 runs, 5 seconds each Memslot count too high for this test, decrease the cap (max is 514) Signed-off-by: Gavin Shan Reviewed-by: Maciej S. Szmigiero Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20221020071209.559062-7-gshan@redhat.com --- .../testing/selftests/kvm/memslot_perf_test.c | 45 +++++++++++++++++-- 1 file changed, 41 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/kvm/memslot_perf_test.c b/tools/testing/selftests/kvm/memslot_perf_test.c index daebc264de5a..2ad40f7c9c08 100644 --- a/tools/testing/selftests/kvm/memslot_perf_test.c +++ b/tools/testing/selftests/kvm/memslot_perf_test.c @@ -239,16 +239,52 @@ static struct vm_data *alloc_vm(void) return data; } +static bool check_slot_pages(uint32_t host_page_size, uint32_t guest_page_size, + uint64_t pages_per_slot, uint64_t rempages) +{ + if (!pages_per_slot) + return false; + + if ((pages_per_slot * guest_page_size) % host_page_size) + return false; + + if ((rempages * guest_page_size) % host_page_size) + return false; + + return true; +} + + +static uint64_t get_max_slots(struct vm_data *data, uint32_t host_page_size) +{ + uint32_t guest_page_size = data->vm->page_size; + uint64_t mempages, pages_per_slot, rempages; + uint64_t slots; + + mempages = data->npages; + slots = data->nslots; + while (--slots > 1) { + pages_per_slot = mempages / slots; + rempages = mempages % pages_per_slot; + if (check_slot_pages(host_page_size, guest_page_size, + pages_per_slot, rempages)) + return slots + 1; /* slot 0 is reserved */ + } + + return 0; +} + static bool prepare_vm(struct vm_data *data, int nslots, uint64_t *maxslots, void *guest_code, uint64_t mem_size, struct timespec *slot_runtime) { uint64_t mempages, rempages; uint64_t guest_addr; - uint32_t slot, guest_page_size; + uint32_t slot, host_page_size, guest_page_size; struct timespec tstart; struct sync_area *sync; + host_page_size = getpagesize(); guest_page_size = vm_guest_mode_params[VM_MODE_DEFAULT].page_size; mempages = mem_size / guest_page_size; @@ -260,12 +296,13 @@ static bool prepare_vm(struct vm_data *data, int nslots, uint64_t *maxslots, TEST_ASSERT(data->npages > 1, "Can't test without any memory"); data->nslots = nslots; data->pages_per_slot = data->npages / data->nslots; - if (!data->pages_per_slot) { - *maxslots = data->npages + 1; + rempages = data->npages % data->nslots; + if (!check_slot_pages(host_page_size, guest_page_size, + data->pages_per_slot, rempages)) { + *maxslots = get_max_slots(data, host_page_size); return false; } - rempages = data->npages % data->nslots; data->hva_slots = malloc(sizeof(*data->hva_slots) * data->nslots); TEST_ASSERT(data->hva_slots, "malloc() fail");