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

[Jingyi Wang <wangjingyi11@huawei.com>]

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@huawei.com>
>>>> ---
>>>>    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 {
>>>>
>>>
>>>
>>> .
>>>
>>
> 
> 
> .
> 

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