| Message ID | 1462380444-11992-1-git-send-email-bill.fischofer@linaro.org |
|---|---|
| State | Accepted |
| Commit | f0ffb68eff2b2ec858b80e809e1766e2081e541a |
| Headers | show |
On 4 May 2016 at 12:47, Bill Fischofer <bill.fischofer@linaro.org> 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 <matias.elo@nokia.com> > Signed-off-by: Bill Fischofer <bill.fischofer@linaro.org> > --- > 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 ? > + > +/** > + * @} > + */ > + > static inline void odp_cpu_pause(void) > { > } > -- > 2.5.0 > > _______________________________________________ > lng-odp mailing list > lng-odp@lists.linaro.org > 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"
On Wed, May 4, 2016 at 2:35 PM, Mike Holmes <mike.holmes@linaro.org> wrote: > > > On 4 May 2016 at 12:47, Bill Fischofer <bill.fischofer@linaro.org> 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 <matias.elo@nokia.com> >> Signed-off-by: Bill Fischofer <bill.fischofer@linaro.org> >> --- >> 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. 32-bit is the minimum for ODP. 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. > > >> + >> +/** >> + * @} >> + */ >> + >> static inline void odp_cpu_pause(void) >> { >> } >> -- >> 2.5.0 >> >> _______________________________________________ >> lng-odp mailing list >> lng-odp@lists.linaro.org >> 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" > > >
On 4 May 2016 at 15:40, Bill Fischofer <bill.fischofer@linaro.org> wrote: > > > On Wed, May 4, 2016 at 2:35 PM, Mike Holmes <mike.holmes@linaro.org> > wrote: > >> >> >> On 4 May 2016 at 12:47, Bill Fischofer <bill.fischofer@linaro.org> 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 <matias.elo@nokia.com> >>> Signed-off-by: Bill Fischofer <bill.fischofer@linaro.org> >>> --- >>> 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 >>> lng-odp@lists.linaro.org >>> 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"
On Wed, May 4, 2016 at 2:53 PM, Mike Holmes <mike.holmes@linaro.org> wrote: > > > On 4 May 2016 at 15:40, Bill Fischofer <bill.fischofer@linaro.org> wrote: > >> >> >> On Wed, May 4, 2016 at 2:35 PM, Mike Holmes <mike.holmes@linaro.org> >> wrote: >> >>> >>> >>> On 4 May 2016 at 12:47, Bill Fischofer <bill.fischofer@linaro.org> >>> 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 <matias.elo@nokia.com> >>>> Signed-off-by: Bill Fischofer <bill.fischofer@linaro.org> >>>> --- >>>> 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 >>>> lng-odp@lists.linaro.org >>>> 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" > > >
On 4 May 2016 at 12:47, Bill Fischofer <bill.fischofer@linaro.org> 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 <matias.elo@nokia.com> > Signed-off-by: Bill Fischofer <bill.fischofer@linaro.org> > Reviewed-by: Mike Holmes <mike.holmes@linaro.org> This combined with the patch to remove the case this exposes where we set ARCH=OS makes sense to me. > --- > 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 > + > +/** > + * @} > + */ > + > static inline void odp_cpu_pause(void) > { > } > -- > 2.5.0 > > _______________________________________________ > lng-odp mailing list > lng-odp@lists.linaro.org > 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"
On 10 May 2016 at 05:01, Mike Holmes <mike.holmes@linaro.org> wrote: > > > On 4 May 2016 at 12:47, Bill Fischofer <bill.fischofer@linaro.org> 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 <matias.elo@nokia.com> >> Signed-off-by: Bill Fischofer <bill.fischofer@linaro.org> >> > > Reviewed-by: Mike Holmes <mike.holmes@linaro.org> > > This combined with the patch to remove the case this exposes where we set > ARCH=OS makes sense to me. > merged > > >> --- >> 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 >> + >> +/** >> + * @} >> + */ >> + >> static inline void odp_cpu_pause(void) >> { >> } >> -- >> 2.5.0 >> >> _______________________________________________ >> lng-odp mailing list >> lng-odp@lists.linaro.org >> 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"
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 + +/** + * @} + */ + static inline void odp_cpu_pause(void) { }
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 <matias.elo@nokia.com> Signed-off-by: Bill Fischofer <bill.fischofer@linaro.org> --- platform/linux-generic/arch/linux/odp/api/cpu_arch.h | 10 ++++++++++ 1 file changed, 10 insertions(+)