Shubha,
The TimerLib class MdePkg/Include/Library/TimerLib.h has a function to convert
TimerLin ticks to ns:
/**
Converts elapsed ticks of performance counter to time in nanoseconds.
This function converts the elapsed ticks of running performance counter to
time value in unit of nanoseconds.
@param Ticks The number of elapsed ticks of running performance counter.
@return The elapsed time in nanoseconds.
**/
UINT64
EFIAPI
GetTimeInNanoSecond (
IN UINT64 Ticks
);
You can use the TimerLib to get a start tick value and end tick value using
/**
Retrieves the current value of a 64-bit free running performance counter.
The counter can either count up by 1 or count down by 1. If the physical
performance counter counts by a larger increment, then the counter values
must be translated. The properties of the counter can be retrieved from
GetPerformanceCounterProperties().
@return The current value of the free running performance counter.
**/
UINT64
EFIAPI
GetPerformanceCounter (
VOID
);
You do have to be aware that the performance counter can count up or down and
Can also rollover. These attributes are available from the following TimerLib
API:
/**
Retrieves the 64-bit frequency in Hz and the range of performance counter
values.
If StartValue is not NULL, then the value that the performance counter starts
with immediately after is it rolls over is returned in StartValue. If
EndValue is not NULL, then the value that the performance counter end with
immediately before it rolls over is returned in EndValue. The 64-bit
frequency of the performance counter in Hz is always returned. If StartValue
is less than EndValue, then the performance counter counts up. If StartValue
is greater than EndValue, then the performance counter counts down. For
example, a 64-bit free running counter that counts up would have a StartValue
of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
@param StartValue The value the performance counter starts with when it
rolls over.
@param EndValue The value that the performance counter ends with before
it rolls over.
@return The frequency in Hz.
**/
UINT64
EFIAPI
GetPerformanceCounterProperties (
OUT UINT64 *StartValue, OPTIONAL
OUT UINT64 *EndValue OPTIONAL
);
I agree with Andrew. If GetPerformanceCounter() is always returning 0, then
you are likely using the wrong TimerLib instance or the HW counter the
TimerLib is accessing has not been initialized yet.
There is a NULL template of the TimerLib in MdePkg called
BaseTimerLibNullTemplate
And it always returns 0. That lib is intended to be a starting point for a new
TimerLib for a new type of timer HW.
Best regards,
Mike
> -----Original Message-----
> From: edk2-devel [mailto:[email protected]] On Behalf Of Andrew
> Fish
> Sent: Thursday, February 4, 2016 9:40 AM
> To: Shubha Ramani <[email protected]>
> Cc: [email protected]
> Subject: Re: [edk2] How do you get current timestamp in ms or ns ?
>
>
> > On Feb 4, 2016, at 9:35 AM, Shubha Ramani <[email protected]> wrote:
> >
> > Hello Andrew Fish ? Anyone ? Does anyone know the answer to this question
> > in EDK2 ?
> > Shubha Shubha D. [email protected]
> > [email protected]
> >
> > On Wednesday, February 3, 2016 10:54 AM, Shubha Ramani
> > <[email protected]>
> wrote:
> >
> >
> > Is there an EDK2 API which returns the current timetamp or current number
> > of ticks
> thathave elapsed in nanoseconds or milliseconds ?
>
> Number of ticks since what? EFI does not have the concept of a timestamp. You
> can use
> gBS->Stall() to get a delay.
>
> > I have tried GetTime() and it returns the time in seconds. I need higher
> > resolution
> thanseconds.
> > I also tried GetPerformanceCounter() but I get 0 for some reason.
>
> You have likely linked against the wrong instance of the TimerLib.
>
> Thanks,
>
> Andrew Fish
>
> > Thanks !
> > Shubha Shubha D. [email protected]
> > [email protected]
> >
> >
> > _______________________________________________
> > edk2-devel mailing list
> > [email protected]
> > https://lists.01.org/mailman/listinfo/edk2-devel
>
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