Re: [PATCH kvm-unit-test 6/6] Add a test for kvm-clock

Zachary Amsden
2010-08-28T01:58:45Z

On 08/26/2010 07:49 PM, Jason Wang wrote:
> This patch implements two tests for kvmclock. First one check whether
> the date of time returned by kvmclock matches the value got from
> host. Second one check whether the cycle of kvmclock grows
> monotonically in smp guest.
>

Technically, it's not monotonic, it's non-decreasing.

> Three parameters were accepted by the test: test loops, seconds
> since 1970-01-01 00:00:00 UTC which could be easily get through date
> +%s and the max accepted offset value between the tod of guest and
> host.
>

This in general looks awesome.

> Signed-off-by: Jason Wang<jasowang@redhat.com>
> ---
> config-x86-common.mak | 6 ++
> x86/README | 2 +
> x86/kvmclock_test.c | 145 +++++++++++++++++++++++++++++++++++++++++++++++++
> x86/unittests.cfg | 5 ++
> 4 files changed, 157 insertions(+), 1 deletions(-)
> create mode 100644 x86/kvmclock_test.c
>
> diff --git a/config-x86-common.mak b/config-x86-common.mak
> index b8ca859..b541c1c 100644
> --- a/config-x86-common.mak
> +++ b/config-x86-common.mak
> @@ -26,7 +26,8 @@ FLATLIBS = lib/libcflat.a $(libgcc)
> tests-common = $(TEST_DIR)/vmexit.flat $(TEST_DIR)/tsc.flat \
> $(TEST_DIR)/smptest.flat $(TEST_DIR)/port80.flat \
> $(TEST_DIR)/realmode.flat $(TEST_DIR)/msr.flat \
> - $(TEST_DIR)/hypercall.flat $(TEST_DIR)/sieve.flat
> + $(TEST_DIR)/hypercall.flat $(TEST_DIR)/sieve.flat \
> + $(TEST_DIR)/kvmclock_test.flat
>
> tests_and_config = $(TEST_DIR)/*.flat $(TEST_DIR)/unittests.cfg
>
> @@ -70,6 +71,9 @@ $(TEST_DIR)/rmap_chain.flat: $(cstart.o) $(TEST_DIR)/rmap_chain.o \
>
> $(TEST_DIR)/svm.flat: $(cstart.o) $(TEST_DIR)/vm.o
>
> +$(TEST_DIR)/kvmclock_test.flat: $(cstart.o) $(TEST_DIR)/kvmclock.o \
> + $(TEST_DIR)/kvmclock_test.o
> +
> arch_clean:
> $(RM) $(TEST_DIR)/*.o $(TEST_DIR)/*.flat \
> $(TEST_DIR)/.*.d $(TEST_DIR)/lib/.*.d $(TEST_DIR)/lib/*.o
> diff --git a/x86/README b/x86/README
> index ab5a2ae..4b90080 100644
> --- a/x86/README
> +++ b/x86/README
> @@ -12,3 +12,5 @@ sieve: heavy memory access with no paging and with paging static and with paging
> smptest: run smp_id() on every cpu and compares return value to number
> tsc: write to tsc(0) and write to tsc(100000000000) and read it back
> vmexit: long loops for each: cpuid, vmcall, mov_from_cr8, mov_to_cr8, inl_pmtimer, ipi, ipi+halt
> +kvmclock_test: monotonic cycle test of kvmclock and a sanity test of
> +wallclock
> diff --git a/x86/kvmclock_test.c b/x86/kvmclock_test.c
> new file mode 100644
> index 0000000..cd80915
> --- /dev/null
> +++ b/x86/kvmclock_test.c
> @@ -0,0 +1,145 @@
> +#include "libcflat.h"
> +#include "smp.h"
> +#include "atomic.h"
> +#include "string.h"
> +#include "kvmclock.h"
> +
> +#define DEFAULT_TEST_LOOPS 100000000L
> +#define DEFAULT_THRESHOLD 60L
> +
> +struct test_info {
> + struct spinlock lock;
> + long loops; /* test loops */
> + u64 warps; /* warp count */
> + long long worst; /* worst warp */
> + volatile cycle_t last; /* last cycle seen by test */
> + atomic_t ncpus; /* number of cpu in the test*/
> +};
> +
> +struct test_info ti[2];
> +
> +static int wallclock_test(long sec, long threshold)
> +{
> + int i;
> + long ksec, offset;
> + struct timespec ts, ts_last;
> +
> + printf("Wallclock test, threshold %ld\n", threshold);
> + kvm_get_wallclock(&ts_last);
> + ksec = ts_last.sec + ts_last.nsec / NSEC_PER_SEC;
> +
> + offset = ksec - sec;
> + printf("Seconds get from host: %ld\n", sec);
> + printf("Seconds get from kvmclock: %ld\n", ksec);
> +
> + if (offset> threshold || offset< -threshold) {
> + printf("Seconds get from kvmclock: %ld\n", ksec);
> + return 1;
> + }
> +
> + for (i=0; i< 100; i++){
> + kvm_get_wallclock(&ts);
> + if (ts.nsec != ts_last.nsec || ts.sec != ts_last.sec){
> + printf ("Inconsistent wall clock returned!\n");
> + return 1;
> + }
> + }
> + return 0;
> +}
> +
> +static void kvm_clock_test(void *data)
> +{
> + struct test_info *hv_test_info = (struct test_info *)data;
> + int i;
> +
> + for (i = 0; i< hv_test_info->loops; i++){
> + cycle_t t0, t1;
> + long long delta;
> +
> + spin_lock(&hv_test_info->lock);
> + t1 = kvm_clock_read();
> + t0 = hv_test_info->last;
> + hv_test_info->last = kvm_clock_read();
> + spin_unlock(&hv_test_info->lock);
> +
> + delta = t1 - t0;
> + if (delta< 0){
> + spin_lock(&hv_test_info->lock);
> + ++hv_test_info->warps;
> + if (delta< hv_test_info->worst){
> + hv_test_info->worst = delta;
> + printf("Worst warp %lld %\n", hv_test_info->worst);
> + }
> + spin_unlock(&hv_test_info->lock);
> + }
> +
> + if (!((unsigned long)i& 31))
> + asm volatile("rep; nop");
> + }
> +
> + atomic_dec(&hv_test_info->ncpus);
> +}
> +
> +static int cycle_test(int ncpus, long loops, struct test_info *ti)
> +{
> + int i;
> +
> + atomic_set(&ti->ncpus, ncpus);
> + ti->loops = loops;
> + for (i = ncpus - 1; i>= 0; i--)
> + on_cpu_async(i, kvm_clock_test, (void *)ti);
> +
> + /* Wait for the end of other vcpu */
> + while(atomic_read(&ti->ncpus))
> + ;
> +
> + printf("Total vcpus: %d\n", ncpus);
> + printf("Test loops: %ld\n", ti->loops);
> + printf("Total warps: %lld\n", ti->warps);
> + printf("Worst warp: %lld\n", ti->worst);
> +
> + return ti->warps ? 1 : 0;
> +}
> +
> +int main(int ac, char **av)
> +{
> + int ncpus = cpu_count();
> + int nerr = 0, i;
> + long loops = DEFAULT_TEST_LOOPS;
> + long sec = 0;
> + long threshold = DEFAULT_THRESHOLD;
> +
> + if (ac> 1)
> + loops = atol(av[1]);
> + if (ac> 2)
> + sec = atol(av[2]);
> + if (ac> 3)
> + threshold = atol(av[3]);
> +
> + smp_init();
> +
> + if (ncpus> MAX_CPU)
> + ncpus = MAX_CPU;
> + for (i = 0; i< ncpus; ++i)
> + on_cpu(i, kvm_clock_init, (void *)0);
> +
> + if (ac> 2)
> + nerr += wallclock_test(sec, threshold);
> +
> + printf("Check the stability of raw cycle\n");
> + pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT
> + | PVCLOCK_RAW_CYCLE_BIT);
>

What is this RAW_CYCLE_BIT ? Did I miss something?