On Mon, 14 Jul 2025 16:50:55 +0200
Igor Mammedov <imammedo@xxxxxxxxxx> wrote:
> test is to be used for benchmarking/validating HPET main counter reading
ignore this one as well, I've just sent v3 with a few fixes
>
> how to run:
> QEMU=/foo/qemu-system-x86_64 x86/run x86/hpet_read_test.flat -smp X
> where X is desired (max) number of logical CPUs on host
>
> it will 1st execute concurrent read benchmark
> and after that it will run torture test enabling/disabling HPET counter,
> while running readers in parallel. Goal is to verify counter that always
> goes up.
>
> Signed-off-by: Igor Mammedov <imammedo@xxxxxxxxxx>
> ---
> v2:
> * fix broken timer going backwards check
> * report # of fails
> * warn if number of vcpus is not sufficient for torture test and skip
> it
> * style fixups
> ---
> x86/Makefile.common | 2 ++
> x86/hpet_read_test.c | 73 ++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 75 insertions(+)
> create mode 100644 x86/hpet_read_test.c
>
> diff --git a/x86/Makefile.common b/x86/Makefile.common
> index 5663a65d..ef0e09a6 100644
> --- a/x86/Makefile.common
> +++ b/x86/Makefile.common
> @@ -101,6 +101,8 @@ tests-common += $(TEST_DIR)/realmode.$(exe) \
> realmode_bits := $(if $(call cc-option,-m16,""),16,32)
> endif
>
> +tests-common += $(TEST_DIR)/hpet_read_test.$(exe)
> +
> test_cases: $(tests-common) $(tests)
>
> $(TEST_DIR)/%.o: CFLAGS += -std=gnu99 -ffreestanding -I $(SRCDIR)/lib -I $(SRCDIR)/lib/x86 -I lib
> diff --git a/x86/hpet_read_test.c b/x86/hpet_read_test.c
> new file mode 100644
> index 00000000..a14194e6
> --- /dev/null
> +++ b/x86/hpet_read_test.c
> @@ -0,0 +1,73 @@
> +#include "libcflat.h"
> +#include "smp.h"
> +#include "asm/barrier.h"
> +#include "x86/atomic.h"
> +
> +#define HPET_ADDR 0xFED00000L
> +#define HPET_COUNTER_ADDR ((uint8_t *)HPET_ADDR + 0xF0UL)
> +#define HPET_CONFIG_ADDR ((uint8_t *)HPET_ADDR + 0x10UL)
> +#define HPET_ENABLE_BIT 0x01UL
> +#define HPET_CLK_PERIOD 10
> +
> +static atomic_t fail;
> +
> +static void hpet_reader(void *data)
> +{
> + uint64_t old_counter = 0, new_counter;
> + long cycles = (long)data;
> +
> + while (cycles--) {
> + new_counter = *(volatile uint64_t *)HPET_COUNTER_ADDR;
> + if (new_counter < old_counter) {
> + atomic_inc(&fail);
> + }
> + old_counter = new_counter;
> + }
> +}
> +
> +static void hpet_writer(void *data)
> +{
> + int i;
> + long cycles = (long)data;
> +
> + for (i = 0; i < cycles; ++i)
> + if (i % 2)
> + *(volatile uint64_t *)HPET_CONFIG_ADDR |= HPET_ENABLE_BIT;
> + else
> + *(volatile uint64_t *)HPET_CONFIG_ADDR &= ~HPET_ENABLE_BIT;
> +}
> +
> +int main(void)
> +{
> + long cycles = 100000;
> + int i;
> + int ncpus;
> + uint64_t start, end, time_ns;
> +
> + ncpus = cpu_count();
> + do {
> + printf("* starting concurrent read bench on %d cpus\n", ncpus);
> + *(volatile uint64_t *)HPET_CONFIG_ADDR |= HPET_ENABLE_BIT;
> + start = *(volatile uint64_t *)HPET_COUNTER_ADDR;
> + on_cpus(hpet_reader, (void *)cycles);
> + end = (*(volatile uint64_t *)HPET_COUNTER_ADDR);
> + time_ns = (end - start) * HPET_CLK_PERIOD;
> + report(time_ns && !atomic_read(&fail),
> + "read test took %lu ms, avg read: %lu ns\n", time_ns/1000000, time_ns/cycles);
> + } while (0);
> +
> + do {
> + printf("* starting enable/disable with concurent readers torture\n");
> + if (ncpus > 2) {
> + for (i = 2; i < ncpus; i++)
> + on_cpu_async(i, hpet_reader, (void *)cycles);
> +
> + on_cpu(1, hpet_writer, (void *)cycles);
> + report(!atomic_read(&fail), "torture test, fails: %u\n", atomic_read(&fail));
> + } else {
> + printf("SKIP: torture test: '-smp X' should be greater than 2\n");
> + }
> + } while (0);
> +
> + return report_summary();
> +}
