| Message ID | 1463511498-855-2-git-send-email-ola.liljedahl@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
On 17 May 2016 at 14:58, Ola Liljedahl <ola.liljedahl@linaro.org> wrote: > (This document/code contribution attached is provided under the terms of > agreement LES-LTM-21309) > > This was sent from a linro address, the contribution agreements are already defined. > Add detection of availability of the -mcx16 compiler flag to > the configure script. This flag is necessary on x86-64 to enable > cpmxchg16. > Implement 128-bit atomics if natively supported by the platform. > 128-bit atomics are used by linux-generic timer implementation > on certain targets (e.g. x86-64) for lock-free implementation. > > Signed-off-by: Ola Liljedahl <ola.liljedahl@linaro.org> > --- > configure.ac | 13 +++++ > .../linux-generic/include/odp_atomic_internal.h | 62 > ++++++++++++++++++++++ > platform/linux-generic/odp_timer.c | 4 +- > 3 files changed, 76 insertions(+), 3 deletions(-) > > diff --git a/configure.ac b/configure.ac > index c59d2d1..7cd6670 100644 > --- a/configure.ac > +++ b/configure.ac > @@ -207,6 +207,19 @@ ODP_CFLAGS="$ODP_CFLAGS -std=c99" > # Extra flags for example to suppress certain warning types > ODP_CFLAGS="$ODP_CFLAGS $ODP_CFLAGS_EXTRA" > > +######################################################################### > +# Check if compiler supports cmpxchng16 > +########################################################################## > +my_save_cflags="$CFLAGS" > +CFLAGS=-mcx16 > +AC_MSG_CHECKING([whether CC supports -mcx16]) > +AC_COMPILE_IFELSE([AC_LANG_PROGRAM([])], > + [AC_MSG_RESULT([yes])] > + [ODP_CFLAGS="$ODP_CFLAGS -mcx16"], > + [AC_MSG_RESULT([no])] > +) > +CFLAGS="$my_save_cflags" > + > ########################################################################## > # Default include setup > ########################################################################## > diff --git a/platform/linux-generic/include/odp_atomic_internal.h > b/platform/linux-generic/include/odp_atomic_internal.h > index 093280f..3c5606c 100644 > --- a/platform/linux-generic/include/odp_atomic_internal.h > +++ b/platform/linux-generic/include/odp_atomic_internal.h > @@ -587,6 +587,68 @@ static inline void > _odp_atomic_flag_clear(_odp_atomic_flag_t *flag) > __atomic_clear(flag, __ATOMIC_RELEASE); > } > > +/* Check if target and compiler supports 128-bit scalars and corresponding > + * exchange and CAS operations */ > +/* GCC on x86-64 needs -mcx16 compiler option */ > +#if defined __SIZEOF_INT128__ && defined > __GCC_HAVE_SYNC_COMPARE_AND_SWAP_16 > + > +/** Preprocessor symbol that indicates support for 128-bit atomics */ > +#define ODP_ATOMIC_U128 > + > +/** An unsigned 128-bit (16-byte) scalar type */ > +typedef __int128 _uint128_t; > + > +/** Atomic 128-bit type */ > +typedef struct { > + _uint128_t v; /**< Actual storage for the atomic variable */ > +} _odp_atomic_u128_t ODP_ALIGNED(16); > + > +/** > + * 16-byte atomic exchange operation > + * > + * @param ptr Pointer to a 16-byte atomic variable > + * @param val Pointer to new value to write > + * @param old Pointer to location for old value > + * @param mmodel Memory model associated with the exchange operation > + */ > +static inline void _odp_atomic_u128_xchg_mm(_odp_atomic_u128_t *ptr, > + _uint128_t *val, > + _uint128_t *old, > + _odp_memmodel_t mm) > +{ > + __atomic_exchange(&ptr->v, val, old, mm); > +} > + > +/** > + * Atomic compare and exchange (swap) of 16-byte atomic variable > + * "Strong" semantics, will not fail spuriously. > + * > + * @param ptr Pointer to a 16-byte atomic variable > + * @param exp Pointer to expected value (updated on failure) > + * @param val Pointer to new value to write > + * @param succ Memory model associated with a successful compare-and-swap > + * operation > + * @param fail Memory model associated with a failed compare-and-swap > + * operation > + * > + * @retval 1 exchange successul > + * @retval 0 exchange failed and '*exp' updated with current value > + */ > +static inline int _odp_atomic_u128_cmp_xchg_mm(_odp_atomic_u128_t *ptr, > + _uint128_t *exp, > + _uint128_t *val, > + _odp_memmodel_t succ, > + _odp_memmodel_t fail) > +{ > + return __atomic_compare_exchange(&ptr->v, exp, val, > + false/*strong*/, succ, fail); > +} > +#endif > + > +/** > + * @} > + */ > + > #ifdef __cplusplus > } > #endif > diff --git a/platform/linux-generic/odp_timer.c > b/platform/linux-generic/odp_timer.c > index 6b84309..41e7195 100644 > --- a/platform/linux-generic/odp_timer.c > +++ b/platform/linux-generic/odp_timer.c > @@ -11,9 +11,7 @@ > * > */ > > -/* Check if compiler supports 16-byte atomics. GCC needs -mcx16 flag on > x86 */ > -/* Using spin lock actually seems faster on Core2 */ > -#ifdef ODP_ATOMIC_U128 > +#if __SIZEOF_POINTER__ != 8 > /* TB_NEEDS_PAD defined if sizeof(odp_buffer_t) != 8 */ > #define TB_NEEDS_PAD > #define TB_SET_PAD(x) ((x).pad = 0) > -- > 2.5.0 > > _______________________________________________ > lng-odp mailing list > lng-odp@lists.linaro.org > https://lists.linaro.org/mailman/listinfo/lng-odp >
diff --git a/configure.ac b/configure.ac index c59d2d1..7cd6670 100644 --- a/configure.ac +++ b/configure.ac @@ -207,6 +207,19 @@ ODP_CFLAGS="$ODP_CFLAGS -std=c99" # Extra flags for example to suppress certain warning types ODP_CFLAGS="$ODP_CFLAGS $ODP_CFLAGS_EXTRA" +######################################################################### +# Check if compiler supports cmpxchng16 +########################################################################## +my_save_cflags="$CFLAGS" +CFLAGS=-mcx16 +AC_MSG_CHECKING([whether CC supports -mcx16]) +AC_COMPILE_IFELSE([AC_LANG_PROGRAM([])], + [AC_MSG_RESULT([yes])] + [ODP_CFLAGS="$ODP_CFLAGS -mcx16"], + [AC_MSG_RESULT([no])] +) +CFLAGS="$my_save_cflags" + ########################################################################## # Default include setup ########################################################################## diff --git a/platform/linux-generic/include/odp_atomic_internal.h b/platform/linux-generic/include/odp_atomic_internal.h index 093280f..3c5606c 100644 --- a/platform/linux-generic/include/odp_atomic_internal.h +++ b/platform/linux-generic/include/odp_atomic_internal.h @@ -587,6 +587,68 @@ static inline void _odp_atomic_flag_clear(_odp_atomic_flag_t *flag) __atomic_clear(flag, __ATOMIC_RELEASE); } +/* Check if target and compiler supports 128-bit scalars and corresponding + * exchange and CAS operations */ +/* GCC on x86-64 needs -mcx16 compiler option */ +#if defined __SIZEOF_INT128__ && defined __GCC_HAVE_SYNC_COMPARE_AND_SWAP_16 + +/** Preprocessor symbol that indicates support for 128-bit atomics */ +#define ODP_ATOMIC_U128 + +/** An unsigned 128-bit (16-byte) scalar type */ +typedef __int128 _uint128_t; + +/** Atomic 128-bit type */ +typedef struct { + _uint128_t v; /**< Actual storage for the atomic variable */ +} _odp_atomic_u128_t ODP_ALIGNED(16); + +/** + * 16-byte atomic exchange operation + * + * @param ptr Pointer to a 16-byte atomic variable + * @param val Pointer to new value to write + * @param old Pointer to location for old value + * @param mmodel Memory model associated with the exchange operation + */ +static inline void _odp_atomic_u128_xchg_mm(_odp_atomic_u128_t *ptr, + _uint128_t *val, + _uint128_t *old, + _odp_memmodel_t mm) +{ + __atomic_exchange(&ptr->v, val, old, mm); +} + +/** + * Atomic compare and exchange (swap) of 16-byte atomic variable + * "Strong" semantics, will not fail spuriously. + * + * @param ptr Pointer to a 16-byte atomic variable + * @param exp Pointer to expected value (updated on failure) + * @param val Pointer to new value to write + * @param succ Memory model associated with a successful compare-and-swap + * operation + * @param fail Memory model associated with a failed compare-and-swap + * operation + * + * @retval 1 exchange successul + * @retval 0 exchange failed and '*exp' updated with current value + */ +static inline int _odp_atomic_u128_cmp_xchg_mm(_odp_atomic_u128_t *ptr, + _uint128_t *exp, + _uint128_t *val, + _odp_memmodel_t succ, + _odp_memmodel_t fail) +{ + return __atomic_compare_exchange(&ptr->v, exp, val, + false/*strong*/, succ, fail); +} +#endif + +/** + * @} + */ + #ifdef __cplusplus } #endif diff --git a/platform/linux-generic/odp_timer.c b/platform/linux-generic/odp_timer.c index 6b84309..41e7195 100644 --- a/platform/linux-generic/odp_timer.c +++ b/platform/linux-generic/odp_timer.c @@ -11,9 +11,7 @@ * */ -/* Check if compiler supports 16-byte atomics. GCC needs -mcx16 flag on x86 */ -/* Using spin lock actually seems faster on Core2 */ -#ifdef ODP_ATOMIC_U128 +#if __SIZEOF_POINTER__ != 8 /* TB_NEEDS_PAD defined if sizeof(odp_buffer_t) != 8 */ #define TB_NEEDS_PAD #define TB_SET_PAD(x) ((x).pad = 0)
(This document/code contribution attached is provided under the terms of agreement LES-LTM-21309) Add detection of availability of the -mcx16 compiler flag to the configure script. This flag is necessary on x86-64 to enable cpmxchg16. Implement 128-bit atomics if natively supported by the platform. 128-bit atomics are used by linux-generic timer implementation on certain targets (e.g. x86-64) for lock-free implementation. Signed-off-by: Ola Liljedahl <ola.liljedahl@linaro.org> --- configure.ac | 13 +++++ .../linux-generic/include/odp_atomic_internal.h | 62 ++++++++++++++++++++++ platform/linux-generic/odp_timer.c | 4 +- 3 files changed, 76 insertions(+), 3 deletions(-)