Nicolas Pitre writes:
> On Thu, 26 Nov 2015, Måns Rullgård wrote:
>
>> Russell King - ARM Linux writes:
>>
>> > On Thu, Nov 26, 2015 at 12:50:08AM +, Måns Rullgård wrote:
>> >> If not calling the function saves an I-cache miss, the benefit can be
>> >> substantial. No, I have no proof of t
On Thu, 26 Nov 2015, Måns Rullgård wrote:
> Russell King - ARM Linux writes:
>
> > On Thu, Nov 26, 2015 at 12:50:08AM +, Måns Rullgård wrote:
> >> If not calling the function saves an I-cache miss, the benefit can be
> >> substantial. No, I have no proof of this being a problem, but it's
>
Russell King - ARM Linux writes:
> On Thu, Nov 26, 2015 at 12:50:08AM +, Måns Rullgård wrote:
>> If not calling the function saves an I-cache miss, the benefit can be
>> substantial. No, I have no proof of this being a problem, but it's
>> something that could happen.
>
> That's a simplistic
On Thu, Nov 26, 2015 at 12:50:08AM +, Måns Rullgård wrote:
> If not calling the function saves an I-cache miss, the benefit can be
> substantial. No, I have no proof of this being a problem, but it's
> something that could happen.
That's a simplistic view of modern CPUs.
As I've already said
Nicolas Pitre writes:
> On Thu, 26 Nov 2015, Måns Rullgård wrote:
>
>> Nicolas Pitre writes:
>>
>> > 3) In fact I was wondering if the overhead of the branch and back is
>> >really significant compared to the non trivial cost of a idiv
>> >instruction and all the complex infrastructur
On Thu, 26 Nov 2015, Måns Rullgård wrote:
> Nicolas Pitre writes:
>
> > On Wed, 25 Nov 2015, Stephen Boyd wrote:
> >
> >> The ARM compiler inserts calls to __aeabi_uidiv() and
> >> __aeabi_idiv() when it needs to perform division on signed and
> >> unsigned integers. If a processor has support f
On Wed, Nov 25, 2015 at 01:51:04PM -0800, Stephen Boyd wrote:
> diff --git a/arch/arm/include/asm/cputype.h b/arch/arm/include/asm/cputype.h
> index 85e374f873ac..48c77d422a0d 100644
> --- a/arch/arm/include/asm/cputype.h
> +++ b/arch/arm/include/asm/cputype.h
> @@ -250,8 +250,14 @@ static inline i
Nicolas Pitre writes:
> On Wed, 25 Nov 2015, Stephen Boyd wrote:
>
>> The ARM compiler inserts calls to __aeabi_uidiv() and
>> __aeabi_idiv() when it needs to perform division on signed and
>> unsigned integers. If a processor has support for the udiv and
>> sdiv division instructions the calls t
On Wed, Nov 25, 2015 at 06:09:13PM -0500, Nicolas Pitre wrote:
> 3) In fact I was wondering if the overhead of the branch and back is
>really significant compared to the non trivial cost of a idiv
>instruction and all the complex infrastructure required to patch
>those branches direc
On Wed, 25 Nov 2015, Stephen Boyd wrote:
> The ARM compiler inserts calls to __aeabi_uidiv() and
> __aeabi_idiv() when it needs to perform division on signed and
> unsigned integers. If a processor has support for the udiv and
> sdiv division instructions the calls to these support routines
> can
The ARM compiler inserts calls to __aeabi_uidiv() and
__aeabi_idiv() when it needs to perform division on signed and
unsigned integers. If a processor has support for the udiv and
sdiv division instructions the calls to these support routines
can be replaced with those instructions. Now that record
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