On 4 May 2016 at 15:40, Bill Fischofer <[email protected]> wrote:

>
>
> On Wed, May 4, 2016 at 2:35 PM, Mike Holmes <[email protected]>
> wrote:
>
>>
>>
>> On 4 May 2016 at 12:47, Bill Fischofer <[email protected]> wrote:
>>
>>> Use a default cache line size of 64 for otherwise unrecognized linux
>>> platforms. This resolves bug
>>> https://bugs.linaro.org/show_bug.cgi?id=2218
>>>
>>> Reported-by: Matias Elo <[email protected]>
>>> Signed-off-by: Bill Fischofer <[email protected]>
>>> ---
>>>  platform/linux-generic/arch/linux/odp/api/cpu_arch.h | 10 ++++++++++
>>>  1 file changed, 10 insertions(+)
>>>
>>> diff --git a/platform/linux-generic/arch/linux/odp/api/cpu_arch.h
>>> b/platform/linux-generic/arch/linux/odp/api/cpu_arch.h
>>> index 1c79f87..29f8889 100644
>>> --- a/platform/linux-generic/arch/linux/odp/api/cpu_arch.h
>>> +++ b/platform/linux-generic/arch/linux/odp/api/cpu_arch.h
>>> @@ -11,6 +11,16 @@
>>>  extern "C" {
>>>  #endif
>>>
>>> +/** @ingroup odp_compiler_optim
>>> + *  @{
>>> + */
>>> +
>>> +#define ODP_CACHE_LINE_SIZE 64
>>>
>>
>> Is this a good number on a 16 bit linux system how about 32 ?
>>
>
> We don't support 16-bit linux.
>

Yes we do, at least we have to assume so :) - it is called linux-generic it
is based on any place linux can run, if some mad Eastern European drinking
a gallon of Vodka makes linux run on a 3 and 1/2 bit CPU we currently
support it by the default ARCH=linux

Additionally nowhere can I find that we state we dont support 16 bit linux.


>  32-bit is the minimum for ODP.
>

This needs to be prominently added to the docs, and then I can agree.


> Also, for cache alignment overaligned is better than underaligned, so if
> the actual cache line size is 32 then using 64-byte alignment does no harm
> since a 64-byte aligned address is also 32-byte aligned.
>

This gets you a silent degradation in the amount of memory you use on a
linux system that happens to be less than 64bits, and also silently an
enforced under alignment on a 128 bit system, the very thing you wanted to
avoid.

I am being nit picky to really get it well defined, I think we assume too
much  that really ODP is run with the OS=linux, on a 64Bit CPU with posix
threading.


>
>
>>
>>
>>> +
>>> +/**
>>> + * @}
>>> + */
>>> +
>>>  static inline void odp_cpu_pause(void)
>>>  {
>>>  }
>>> --
>>> 2.5.0
>>>
>>> _______________________________________________
>>> lng-odp mailing list
>>> [email protected]
>>> https://lists.linaro.org/mailman/listinfo/lng-odp
>>>
>>
>>
>>
>> --
>> Mike Holmes
>> Technical Manager - Linaro Networking Group
>> Linaro.org <http://www.linaro.org/> *│ *Open source software for ARM SoCs
>> "Work should be fun and collaborative, the rest follows"
>>
>>
>>
>


-- 
Mike Holmes
Technical Manager - Linaro Networking Group
Linaro.org <http://www.linaro.org/> *│ *Open source software for ARM SoCs
"Work should be fun and collaborative, the rest follows"
_______________________________________________
lng-odp mailing list
[email protected]
https://lists.linaro.org/mailman/listinfo/lng-odp

Reply via email to