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Message-ID: <CADrL8HWrgbV+coEod_EUnvG27HX3WtJDMua3FPiReCRCtXaNhw@mail.gmail.com>
Date: Tue, 25 Mar 2025 11:01:29 -0700
From: James Houghton <jthoughton@...gle.com>
To: Maxim Levitsky <mlevitsk@...hat.com>
Cc: kvm@...r.kernel.org, Muhammad Usama Anjum <usama.anjum@...labora.com>,
linux-kernel@...r.kernel.org, Sean Christopherson <seanjc@...gle.com>,
Shuah Khan <shuah@...nel.org>, Claudio Imbrenda <imbrenda@...ux.ibm.com>,
Oliver Upton <oliver.upton@...ux.dev>, Paolo Bonzini <pbonzini@...hat.com>,
linux-kselftest@...r.kernel.org, Anup Patel <anup@...infault.org>
Subject: Re: [PATCH v2 2/2] KVM: selftests: access_tracking_perf_test: add
option to skip the sanity check
On Mon, Mar 24, 2025 at 6:57 PM Maxim Levitsky <mlevitsk@...hat.com> wrote:
>
> Add an option to skip sanity check of number of still idle pages,
> and set it by default to skip, in case hypervisor or NUMA balancing
> is detected.
>
> Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
Thanks Maxim! I'm still working on a respin of this test with MGLRU
integration, like [1]. Sorry it's taking me so long. I'll apply my
changes on top of yours.
[1]: https://lore.kernel.org/kvm/20241105184333.2305744-12-jthoughton@google.com/
> ---
> .../selftests/kvm/access_tracking_perf_test.c | 33 ++++++++++++++++---
> .../testing/selftests/kvm/include/test_util.h | 1 +
> tools/testing/selftests/kvm/lib/test_util.c | 7 ++++
> 3 files changed, 37 insertions(+), 4 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/access_tracking_perf_test.c b/tools/testing/selftests/kvm/access_tracking_perf_test.c
> index 3c7defd34f56..6d50c829f00c 100644
> --- a/tools/testing/selftests/kvm/access_tracking_perf_test.c
> +++ b/tools/testing/selftests/kvm/access_tracking_perf_test.c
> @@ -65,6 +65,8 @@ static int vcpu_last_completed_iteration[KVM_MAX_VCPUS];
> /* Whether to overlap the regions of memory vCPUs access. */
> static bool overlap_memory_access;
>
> +static int warn_on_too_many_idle_pages = -1;
> +
> struct test_params {
> /* The backing source for the region of memory. */
> enum vm_mem_backing_src_type backing_src;
> @@ -184,11 +186,10 @@ static void mark_vcpu_memory_idle(struct kvm_vm *vm,
> * are cached and the guest won't see the "idle" bit cleared.
> */
> if (still_idle >= pages / 10) {
> -#ifdef __x86_64__
> - TEST_ASSERT(this_cpu_has(X86_FEATURE_HYPERVISOR),
> + TEST_ASSERT(warn_on_too_many_idle_pages,
I think this assertion is flipped (or how warn_on_too_many_idle_pages
is being set is flipped, see below).
> "vCPU%d: Too many pages still idle (%lu out of %lu)",
> vcpu_idx, still_idle, pages);
> -#endif
> +
> printf("WARNING: vCPU%d: Too many pages still idle (%lu out of %lu), "
> "this will affect performance results.\n",
> vcpu_idx, still_idle, pages);
> @@ -342,6 +343,8 @@ 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(" -w: Skip or force enable the check that after dirtying the guest memory, most (90%%) of \n"
> + "it is reported as dirty again (0/1)");
> backing_src_help("-s");
> puts("");
> exit(0);
> @@ -359,7 +362,7 @@ int main(int argc, char *argv[])
>
> guest_modes_append_default();
>
> - while ((opt = getopt(argc, argv, "hm:b:v:os:")) != -1) {
> + while ((opt = getopt(argc, argv, "hm:b:v:os:w:")) != -1) {
> switch (opt) {
> case 'm':
> guest_modes_cmdline(optarg);
> @@ -376,6 +379,11 @@ int main(int argc, char *argv[])
> case 's':
> params.backing_src = parse_backing_src_type(optarg);
> break;
> + case 'w':
> + warn_on_too_many_idle_pages =
> + atoi_non_negative("1 - enable warning, 0 - disable",
> + optarg);
We still get a "warning" either way, right? Maybe this should be
called "fail_on_too_many_idle_pages" (in which case the above
assertion is indeed flipped). Or "warn_on_too_many_idle_pages" should
mean *only* warn, i.e., *don't* fail, in which case, below we need to
flip how we set it below.
> + break;
> case 'h':
> default:
> help(argv[0]);
> @@ -386,6 +394,23 @@ int main(int argc, char *argv[])
> page_idle_fd = open("/sys/kernel/mm/page_idle/bitmap", O_RDWR);
> __TEST_REQUIRE(page_idle_fd >= 0,
> "CONFIG_IDLE_PAGE_TRACKING is not enabled");
> + if (warn_on_too_many_idle_pages == -1) {
> +#ifdef __x86_64__
> + if (this_cpu_has(X86_FEATURE_HYPERVISOR)) {
> + printf("Skipping idle page count sanity check, because the test is run nested\n");
> + warn_on_too_many_idle_pages = 0;
> + } else
> +#endif
> + if (is_numa_balancing_enabled()) {
> + printf("Skipping idle page count sanity check, because NUMA balance is enabled\n");
> + warn_on_too_many_idle_pages = 0;
> + } else {
> + warn_on_too_many_idle_pages = 1;
> + }
> + } else if (!warn_on_too_many_idle_pages) {
> + printf("Skipping idle page count sanity check, because this was requested by the user\n");
> + }
> +
> close(page_idle_fd);
>
> for_each_guest_mode(run_test, ¶ms);
> diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
> index 3e473058849f..1bc9b0a92427 100644
> --- a/tools/testing/selftests/kvm/include/test_util.h
> +++ b/tools/testing/selftests/kvm/include/test_util.h
> @@ -153,6 +153,7 @@ bool is_backing_src_hugetlb(uint32_t i);
> void backing_src_help(const char *flag);
> enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name);
> long get_run_delay(void);
> +bool is_numa_balancing_enabled(void);
>
> /*
> * Whether or not the given source type is shared memory (as opposed to
> diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
> index 3dc8538f5d69..03eb99af9b8d 100644
> --- a/tools/testing/selftests/kvm/lib/test_util.c
> +++ b/tools/testing/selftests/kvm/lib/test_util.c
> @@ -176,6 +176,13 @@ size_t get_trans_hugepagesz(void)
> return get_sysfs_val("/sys/kernel/mm/transparent_hugepage/hpage_pmd_size");
> }
>
> +bool is_numa_balancing_enabled(void)
> +{
> + if (!test_sysfs_path("/proc/sys/kernel/numa_balancing"))
> + return false;
> + return get_sysfs_val("/proc/sys/kernel/numa_balancing") == 1;
> +}
> +
> size_t get_def_hugetlb_pagesz(void)
> {
> char buf[64];
> --
> 2.26.3
>
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