This header implements 64 bit counters that are NOT atomic but are safe against load/store splits on 32 bit platforms.
Signed-off-by: Stephen Hemminger <step...@networkplumber.org> Acked-by: Morten Brørup <m...@smartsharesystems.com> --- lib/eal/include/meson.build | 1 + lib/eal/include/rte_counter.h | 98 +++++++++++++++++++++++++++++++++++ 2 files changed, 99 insertions(+) create mode 100644 lib/eal/include/rte_counter.h diff --git a/lib/eal/include/meson.build b/lib/eal/include/meson.build index e94b056d46..c070dd0079 100644 --- a/lib/eal/include/meson.build +++ b/lib/eal/include/meson.build @@ -12,6 +12,7 @@ headers += files( 'rte_class.h', 'rte_common.h', 'rte_compat.h', + 'rte_counter.h', 'rte_debug.h', 'rte_dev.h', 'rte_devargs.h', diff --git a/lib/eal/include/rte_counter.h b/lib/eal/include/rte_counter.h new file mode 100644 index 0000000000..d623195d63 --- /dev/null +++ b/lib/eal/include/rte_counter.h @@ -0,0 +1,98 @@ +/* SPDX-License-Identifier: BSD-3-Clause + * Copyright (c) Stephen Hemminger <step...@networkplumber.org> + */ + +#ifndef _RTE_COUNTER_H_ +#define _RTE_COUNTER_H_ + +#ifdef __cplusplus +extern "C" { +#endif + +/** + * @file + * RTE Counter + * + * A counter is 64 bit value that is safe from split read/write + * on 32 bit platforms. It assumes that only one cpu at a time + * will update the counter, and another CPU may want to read it. + * + * This is a much weaker guarantee than full atomic variables + * but is faster since no locked operations are required for update. + */ + +#ifdef RTE_ARCH_64 +/* + * On a platform that can support native 64 bit type, no special handling. + * These are just wrapper around 64 bit value. + */ +typedef uint64_t rte_counter64_t; + +/** + * Add value to counter. + */ +__rte_experimental +static inline void +rte_counter64_add(rte_counter64_t *counter, uint32_t val) +{ + *counter += val; +} + +__rte_experimental +static inline uint64_t +rte_counter64_fetch(const rte_counter64_t *counter) +{ + return *counter; +} + +__rte_experimental +static inline void +rte_counter64_set(rte_counter64_t *counter, uint64_t val) +{ + *counter = val; +} + +#else + +#include <rte_stdatomic.h> + +/* + * On a 32 bit platform need to use atomic to force the compler to not + * split 64 bit read/write. + */ +typedef RTE_ATOMIC(uint64_t) rte_counter64_t; + +__rte_experimental +static inline void +rte_counter64_add(rte_counter64_t *counter, uint32_t val) +{ + rte_atomic_fetch_add_explicit(counter, val, rte_memory_order_relaxed); +} + +__rte_experimental +static inline uint64_t +rte_counter64_fetch(const rte_counter64_t *counter) +{ + return rte_atomic_load_explicit(counter, rte_memory_order_consume); +} + +__rte_experimental +static inline void +rte_counter64_set(rte_counter64_t *counter, uint64_t val) +{ + rte_atomic_store_explicit(counter, val, rte_memory_order_release); +} +#endif + +__rte_experimental +static inline void +rte_counter64_reset(rte_counter64_t *counter) +{ + rte_counter64_set(counter, 0); +} + +#ifdef __cplusplus +} +#endif + +#endif /* _RTE_COUNTER_H_ */ -- 2.43.0