[PATCH 6/6] aarch64: Add hp-timing.h

[Andreas Schwab]

pinskia@gmail.com writes:

>> On Jul 21, 2014, at 4:41 AM, Andreas Schwab <schwab@suse.de> wrote:
>> 
>> Richard Henderson <rth@twiddle.net> writes:
>> 
>>> +/* Sync the instruction stream, and read from the virtual cycle counter.  */
>>> +#define HP_TIMING_NOW(Var) \
>>> +  __asm__ __volatile__ ("isb; mrs %0, cntvct_el0" : "=r" (Var))
>> 
>> According to https://bugs.launchpad.net/bugs/1344320 the generic timers
>> are not part of the kernel-to-userspace contract.
>
>
> I think this is bogus for the kernel folks not allow a high precision timer in user space. Timers like this are needed for micro-benchmarking compiler changes along with other libc changes. 

According to the qemu bug the timers are optional.

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
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