Re: [kvm-unit-tests PATCH v2 8/8] arm64: microbench: Add vtimer latency test

[Jingyi Wang <wangjingyi11@xxxxxxxxxx>]

Hi Eric,

On 7/3/2020 3:45 PM, Auger Eric wrote:
> Hi Jingyi,
>
> On 7/3/20 9:41 AM, Jingyi Wang wrote:
> > Hi Eric, Drew,
> >
> > On 7/2/2020 9:36 PM, Auger Eric wrote:
> > > Hi Jingyi,
> > >
> > > On 7/2/20 5:01 AM, Jingyi Wang wrote:
> > > > Trigger PPIs by setting up a 10msec timer and test the latency.
> > >
> > > so for each iteration the accumulated valued is 10 ms + latency, right?
> > > and what is printed at the end does include the accumulated periods.
> > > Wouldn't it make sense to have a test->post() that substract this value.
> > > You would need to store the actual number of iterations.
> > >
> > > Thanks
> > >
> > > Eric
> >
> > That's right, the result indicates 10ms + latency, which is a 10msec
> > timer actually costs. I think using the difference instead of the total
> > time cost can be a little confusing here. Maybe we can use test->post()
> > to get the latency and print an extra result in logs? Do you have any
> > opinions on that?
>
> for other interrupts you only print the latency, right? Here if I
> understand correctly you use the timer to trigger the PPI but still you
> care about the latency, hence my suggestion to only print the latency.
>
> Thanks
>
> Eric

Okay, I will create a separate patch to extract the vtimer difference
in the next version, thanks for you suggestion.

Thanks,
Jingyi

> > Thanks,
> > Jingyi
> >
> > > > Signed-off-by: Jingyi Wang <wangjingyi11@xxxxxxxxxx>
> > > > ---
> > > >    arm/micro-bench.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++-
> > > >    1 file changed, 55 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/arm/micro-bench.c b/arm/micro-bench.c
> > > > index 4c962b7..6822084 100644
> > > > --- a/arm/micro-bench.c
> > > > +++ b/arm/micro-bench.c
> > > > @@ -23,8 +23,13 @@
> > > >    #include <asm/gic-v3-its.h>
> > > >      #define NTIMES (1U << 16)
> > > > +#define NTIMES_MINOR (1U << 8)
> > > >    #define MAX_NS (5 * 1000 * 1000 * 1000UL)
> > > >    +#define IRQ_VTIMER        27
> > > > +#define ARCH_TIMER_CTL_ENABLE    (1 << 0)
> > > > +#define ARCH_TIMER_CTL_IMASK    (1 << 1)
> > > > +
> > > >    static u32 cntfrq;
> > > >      static volatile bool irq_ready, irq_received;
> > > > @@ -33,9 +38,16 @@ static void (*write_eoir)(u32 irqstat);
> > > >      static void gic_irq_handler(struct pt_regs *regs)
> > > >    {
> > > > +    u32 irqstat = gic_read_iar();
> > > >        irq_ready = false;
> > > >        irq_received = true;
> > > > -    gic_write_eoir(gic_read_iar());
> > > > +    gic_write_eoir(irqstat);
> > > > +
> > > > +    if (irqstat == IRQ_VTIMER) {
> > > > +        write_sysreg((ARCH_TIMER_CTL_IMASK | ARCH_TIMER_CTL_ENABLE),
> > > > +                 cntv_ctl_el0);
> > > > +        isb();
> > > > +    }
> > > >        irq_ready = true;
> > > >    }
> > > >    @@ -189,6 +201,47 @@ static void lpi_exec(void)
> > > >        assert_msg(irq_received, "failed to receive LPI in time, but
> > > > received %d successfully\n", received);
> > > >    }
> > > >    +static bool timer_prep(void)
> > > > +{
> > > > +    static void *gic_isenabler;
> > > > +
> > > > +    gic_enable_defaults();
> > > > +    install_irq_handler(EL1H_IRQ, gic_irq_handler);
> > > > +    local_irq_enable();
> > > > +
> > > > +    gic_isenabler = gicv3_sgi_base() + GICR_ISENABLER0;
> > > > +    writel(1 << 27, gic_isenabler);
> > > > +    write_sysreg(ARCH_TIMER_CTL_ENABLE, cntv_ctl_el0);
> > > > +    isb();
> > > > +
> > > > +    gic_prep_common();
> > > > +    return true;
> > > > +}
> > > > +
> > > > +static void timer_exec(void)
> > > > +{
> > > > +    u64 before_timer;
> > > > +    u64 timer_10ms;
> > > > +    unsigned tries = 1 << 28;
> > > > +    static int received = 0;
> > > > +
> > > > +    irq_received = false;
> > > > +
> > > > +    before_timer = read_sysreg(cntvct_el0);
> > > > +    timer_10ms = cntfrq / 100;
> > > > +    write_sysreg(before_timer + timer_10ms, cntv_cval_el0);
> > > > +    write_sysreg(ARCH_TIMER_CTL_ENABLE, cntv_ctl_el0);
> > > > +    isb();
> > > > +
> > > > +    while (!irq_received && tries--)
> > > > +        cpu_relax();
> > > > +
> > > > +    if (irq_received)
> > > > +        ++received;
> > > > +
> > > > +    assert_msg(irq_received, "failed to receive PPI in time, but
> > > > received %d successfully\n", received);
> > > > +}
> > > > +
> > > >    static void hvc_exec(void)
> > > >    {
> > > >        asm volatile("mov w0, #0x4b000000; hvc #0" ::: "w0");
> > > > @@ -236,6 +289,7 @@ static struct exit_test tests[] = {
> > > >        {"ipi",            ipi_prep,    ipi_exec,        NTIMES,
> > > > true},
> > > >        {"ipi_hw",        ipi_hw_prep,    ipi_exec,
> > > > NTIMES,        true},
> > > >        {"lpi",            lpi_prep,    lpi_exec,        NTIMES,
> > > > true},
> > > > +    {"timer_10ms",        timer_prep,    timer_exec,
> > > > NTIMES_MINOR,    true},
> > > >    };
> > > >      struct ns_time {
> > >
> > >
> > > .
>
>
> .