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KVM: selftests: Report per-vcpu demand paging rate from demand paging test

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Using the overall demand paging rate to measure performance can be
slightly misleading when vCPU accesses are not overlapped. Adding more
vCPUs will (usually) increase the overall demand paging rate even
if performance remains constant or even degrades on a per-vcpu basis. As
such, it makes sense to report both the total and per-vcpu paging rates.

Signed-off-by: Anish Moorthy <amoorthy@google.com>
Link: https://lore.kernel.org/r/20240215235405.368539-11-amoorthy@google.com
[sean: fix formatting]
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Anish Moorthy
2024-02-15 23:54:01 +00:00
committed by Sean Christopherson
parent fec50db703
commit 2ca76c12c4
1 changed files with 9 additions and 4 deletions
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tools/testing/selftests/kvm/demand_paging_test.c
+9 -4
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@@ -133,6 +133,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
struct uffd_desc **uffd_descs = NULL;
struct timespec start;
struct timespec ts_diff;
double vcpu_paging_rate;
struct kvm_vm *vm;
int i;
@@ -191,11 +192,15 @@ static void run_test(enum vm_guest_mode mode, void *arg)
uffd_stop_demand_paging(uffd_descs[i]);
}
pr_info("Total guest execution time: %ld.%.9lds\n",
pr_info("Total guest execution time:\t%ld.%.9lds\n",
ts_diff.tv_sec, ts_diff.tv_nsec);
pr_info("Overall demand paging rate: %f pgs/sec\n",
memstress_args.vcpu_args[0].pages * nr_vcpus /
((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / NSEC_PER_SEC));
vcpu_paging_rate = memstress_args.vcpu_args[0].pages /
((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / NSEC_PER_SEC);
pr_info("Per-vcpu demand paging rate:\t%f pgs/sec/vcpu\n",
vcpu_paging_rate);
pr_info("Overall demand paging rate:\t%f pgs/sec\n",
vcpu_paging_rate * nr_vcpus);
memstress_destroy_vm(vm);