On Wed, May 4, 2016 at 2:53 PM, Mike Holmes <[email protected]> wrote:
> > > 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. > I can't find an explicit reference to this in the ODP archives but I recall very early in the project we decided to restrict ODP to a minimum of 32-bit support because (a) none of our members had 16-bit HW and (b) we didn't have any tools or systems to test ODP in 16-bit linux environments. If we wanted to add such support it would be a major effort for little return. The current linux-generic implementation, for example, assumes a minimum of 32-bit addressing in many places. We can certainly add a documentation note to the Implementer's Guide that ODP is designed for systems that use 32-bit or 64-bit addressing. > > >> 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. > I think you're trying to turn a bug-fix into an architecture discussion. If someone has a better "guess" as to what cache line size to use for an unknown and unspecified architecture I'm happy to change this. But the issue is that the #define is missing, which causes the compile error Matias reported. > > >> >> >>> >>> >>>> + >>>> +/** >>>> + * @} >>>> + */ >>>> + >>>> 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" > > >
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