Re: [Qemu-devel] [PATCH] replaced get_ticks_per_sec() with constant

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Sat, Mar 28, 2015 at 06:22:11PM +0200, Emil Condrea wrote:
> diff --git a/target-arm/helper.c b/target-arm/helper.c
> index 10886c5..504530a 100644
> --- a/target-arm/helper.c
> +++ b/target-arm/helper.c
> @@ -649,7 +649,7 @@ void pmccntr_sync(CPUARMState *env)
>      uint64_t temp_ticks;
>  
>      temp_ticks = muldiv64(qemu_clock_get_us(QEMU_CLOCK_VIRTUAL),
> -                          get_ticks_per_sec(), 1000000);
> +                          NSEC_PER_SEC, 1000000);
>  
>      if (env->cp15.c9_pmcr & PMCRD) {
>          /* Increment once every 64 processor clock cycles */
> @@ -688,7 +688,7 @@ static uint64_t pmccntr_read(CPUARMState *env, const ARMCPRegInfo *ri)
>      }
>  
>      total_ticks = muldiv64(qemu_clock_get_us(QEMU_CLOCK_VIRTUAL),
> -                           get_ticks_per_sec(), 1000000);
> +                           NSEC_PER_SEC, 1000000);
>  
>      if (env->cp15.c9_pmcr & PMCRD) {
>          /* Increment once every 64 processor clock cycles */
> @@ -709,7 +709,7 @@ static void pmccntr_write(CPUARMState *env, const ARMCPRegInfo *ri,
>      }
>  
>      total_ticks = muldiv64(qemu_clock_get_us(QEMU_CLOCK_VIRTUAL),
> -                           get_ticks_per_sec(), 1000000);
> +                           NSEC_PER_SEC, 1000000);

Peter: I wonder why the muldiv64() expression is necessary.  Is it
intentionally returning the microsecond clock converted to nanoseconds?

Perhaps the expression should be replaced with just
qemu_get_clock_ns(QEMU_CLOCK_VIRTUAL)?

Or if microsecond precision is required, use qemu_get_clock_us() * 1000.

Stefan

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