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SubjectRe: [PATCH 3/6] KVM: selftests: memslot_perf_test: Probe memory slots for once
On 14.10.2022 09:19, Gavin Shan wrote:
> prepare_vm() is called in every iteration and run. The allowed memory
> slots (KVM_CAP_NR_MEMSLOTS) are probed for multiple times. It's not
> free and unnecessary.
>
> Move the probing logic for the allowed memory slots to parse_args()
> for once, which is upper layer of prepare_vm().
>
> No functional change intended.
>
> Signed-off-by: Gavin Shan <gshan@redhat.com>
> ---
> .../testing/selftests/kvm/memslot_perf_test.c | 29 ++++++++++---------
> 1 file changed, 16 insertions(+), 13 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/memslot_perf_test.c b/tools/testing/selftests/kvm/memslot_perf_test.c
> index dcb492b3f27b..d5aa9148f96f 100644
> --- a/tools/testing/selftests/kvm/memslot_perf_test.c
> +++ b/tools/testing/selftests/kvm/memslot_perf_test.c
> @@ -245,27 +245,17 @@ static bool prepare_vm(struct vm_data *data, int nslots, uint64_t *maxslots,
> void *guest_code, uint64_t mempages,
> struct timespec *slot_runtime)
> {
> - uint32_t max_mem_slots;
> uint64_t rempages;
> uint64_t guest_addr;
> uint32_t slot;
> struct timespec tstart;
> struct sync_area *sync;
>
> - max_mem_slots = kvm_check_cap(KVM_CAP_NR_MEMSLOTS);
> - TEST_ASSERT(max_mem_slots > 1,
> - "KVM_CAP_NR_MEMSLOTS should be greater than 1");
> - TEST_ASSERT(nslots > 1 || nslots == -1,
> - "Slot count cap should be greater than 1");
> - if (nslots != -1)
> - max_mem_slots = min(max_mem_slots, (uint32_t)nslots);
> - pr_info_v("Allowed number of memory slots: %"PRIu32"\n", max_mem_slots);
> -
> TEST_ASSERT(mempages > 1,
> "Can't test without any memory");
>
> data->npages = mempages;
> - data->nslots = max_mem_slots - 1;
> + data->nslots = nslots;
> data->pages_per_slot = mempages / data->nslots;
> if (!data->pages_per_slot) {
> *maxslots = mempages + 1;
> @@ -885,8 +875,8 @@ static bool parse_args(int argc, char *argv[],
> break;
> case 's':
> targs->nslots = atoi(optarg);
> - if (targs->nslots <= 0 && targs->nslots != -1) {
> - pr_info("Slot count cap has to be positive or -1 for no cap\n");
> + if (targs->nslots <= 1 && targs->nslots != -1) {
> + pr_info("Slot count cap must be larger than 1 or -1 for no cap\n");
> return false;
> }
> break;
> @@ -932,6 +922,19 @@ static bool parse_args(int argc, char *argv[],
> return false;
> }
>
> + /* Memory slot 0 is reserved */
> + if (targs->nslots == -1) {
> + targs->nslots = kvm_check_cap(KVM_CAP_NR_MEMSLOTS) - 1;
> + if (targs->nslots < 1) {
> + pr_info("KVM_CAP_NR_MEMSLOTS should be greater than 1\n");
> + return false;
> + }
> + } else {
> + targs->nslots--;
> + }
> +
> + pr_info_v("Number of memory slots: %d\n", targs->nslots);
> +

Can't see any capping of the command line provided slot count to
KVM_CAP_NR_MEMSLOTS value, like the old code did.

> return true;
> }
>

Thanks,
Maciej

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