Re: Build issue on arm: undefined reference to `get_cpu_clock'

[Jens Axboe <jaxboe@fusionio.com>]

On 08/12/2010 05:04 AM, Michael Opdenacker wrote:
> Hi Jens,
> 
> On 08/10/2010 08:04 PM, Jens Axboe wrote:
>> On 08/10/2010 08:11 AM, Michael Opdenacker wrote:
>>> The get_cpu_clock function is only defined in
>>> arch/arch-ia64.h
>>> arch/arch-x86.h
>>> arch/arch-x86_64.h
>>>
>>> How are other architectures supported? I don't understand fio can
>>> support them without defining the get_cpu_clock() function.
>>>
>>> I did my tests on version 1.42, but faced the same issues with the
>>> latest git version.
>>>     
>> Indeed, dunno what happened there. I'll take a look.
>>   
> I have seen your addition of get_cpu_clock() for the ppc architecture.
> 
> By the way, wouldn't it be more portable to use the POSIX
> clock_gettime() function instead of reading an architecture dependent
> register? At least, this is recommended on
> http://en.wikipedia.org/wiki/Time_Stamp_Counter

Of course using clock_gettime() would be more portable. The
point of the CPU clock is speed. If you are testing IOPS into
the ranges of millions and doing ~5 clock calls per IO, then
portability takes a back seat to speed.

But arm needs to work of course, I will commit a patch to
fix it as soon as I can.

-- 
Jens Axboe


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