Ola, can you please review the final version?
Maxim.
On 11/26/2015 11:56, Savolainen, Petri (Nokia - FI/Espoo) wrote:
ping.
-----Original Message-----
From: lng-odp [mailto:lng-odp-boun...@lists.linaro.org] On Behalf Of EXT
Petri Savolainen
Sent: Thursday, November 12, 2015 10:30 AM
To: lng-odp@lists.linaro.org
Subject: [lng-odp] [API-NEXT PATCH v3] api: atomic: added
atomic_lock_free_u64
Platforms may support some uint64 operations lock-free and
others not. For example, inc_64 can be natively supported but
cas_64 (or max_64/min_64) not. User may be able to switch to
32 bit variables when a 64 bit operation uses locks. The same
atomic operation struture could be used for platform init to guide
lock vs. lock-free implementation (e.g. if cas_64 is never
called, inc_64 can be lock-free).
Signed-off-by: Petri Savolainen <petri.savolai...@nokia.com>
---
include/odp/api/atomic.h | 48
+++++++++++++++++++++++++++++++++++++
platform/linux-generic/Makefile.am | 1 +
platform/linux-generic/odp_atomic.c | 24 +++++++++++++++++++
3 files changed, 73 insertions(+)
create mode 100644 platform/linux-generic/odp_atomic.c
diff --git a/include/odp/api/atomic.h b/include/odp/api/atomic.h
index 316f13a..5e897c1 100644
--- a/include/odp/api/atomic.h
+++ b/include/odp/api/atomic.h
@@ -388,6 +388,54 @@ void odp_atomic_add_rls_u32(odp_atomic_u32_t *atom,
uint32_t val);
void odp_atomic_sub_rls_u32(odp_atomic_u32_t *atom, uint32_t val);
/**
+ * Atomic operations
+ *
+ * Atomic operations listed in a bit field structure.
+ */
+typedef union odp_atomic_op_t {
+ /** Operation flags */
+ struct {
+ uint32_t init : 1; /**< Init atomic variable */
+ uint32_t load : 1; /**< Atomic load */
+ uint32_t store : 1; /**< Atomic store */
+ uint32_t fetch_add : 1; /**< Atomic fetch and add */
+ uint32_t add : 1; /**< Atomic add */
+ uint32_t fetch_sub : 1; /**< Atomic fetch and substract */
+ uint32_t sub : 1; /**< Atomic substract */
+ uint32_t fetch_inc : 1; /**< Atomic fetch and increment */
+ uint32_t inc : 1; /**< Atomic increment */
+ uint32_t fetch_dec : 1; /**< Atomic fetch and decrement */
+ uint32_t dec : 1; /**< Atomic decrement */
+ uint32_t min : 1; /**< Atomic minimum */
+ uint32_t max : 1; /**< Atomic maximum */
+ uint32_t cas : 1; /**< Atomic compare and swap */
+ } op;
+
+ /** All bits of the bit field structure.
+ * Operation flag mapping is architecture specific. This field can
be
+ * used to set/clear all flags, or bitwise operations over the
entire
+ * structure. */
+ uint32_t all_bits;
+} odp_atomic_op_t;
+
+/**
+ * Query which atomic uint64 operations are lock-free
+ *
+ * Lock-free implementations have higher performance and scale better
than
+ * implementations using locks. User can decide to use e.g. uint32 atomic
+ * variables instead of uint64 to optimize performance on platforms that
+ * implement a performance critical operation using locks.
+ *
+ * @param atomic_op Pointer to atomic operation structure for storing
+ * operation flags. All bits are initialized to zero
during
+ * the operation. The parameter is ignored when NULL.
+ * @retval 0 None of the operations are lock-free
+ * @retval 1 Some of the operations are lock-free
+ * @retval 2 All operations are lock-free
+ */
+int odp_atomic_lock_free_u64(odp_atomic_op_t *atomic_op);
+
+/**
* @}
*/
diff --git a/platform/linux-generic/Makefile.am b/platform/linux-
generic/Makefile.am
index a6b6029..0b7234e 100644
--- a/platform/linux-generic/Makefile.am
+++ b/platform/linux-generic/Makefile.am
@@ -151,6 +151,7 @@ noinst_HEADERS = \
${srcdir}/Makefile.inc
__LIB__libodp_la_SOURCES = \
+ odp_atomic.c \
odp_barrier.c \
odp_buffer.c \
odp_classification.c \
diff --git a/platform/linux-generic/odp_atomic.c b/platform/linux-
generic/odp_atomic.c
new file mode 100644
index 0000000..996d09a
--- /dev/null
+++ b/platform/linux-generic/odp_atomic.c
@@ -0,0 +1,24 @@
+/* Copyright (c) 2015, Linaro Limited
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <odp/atomic.h>
+
+int odp_atomic_lock_free_u64(odp_atomic_op_t *atomic_op)
+{
+#if __GCC_ATOMIC_LLONG_LOCK_FREE < 2
+ /* All operations have locks */
+ if (atomic_op)
+ atomic_op->all_bits = 0;
+
+ return 0;
+#else
+ /* All operations are lock-free */
+ if (atomic_op)
+ atomic_op->all_bits = ~((uint32_t)0);
+
+ return 2;
+#endif
+}
--
2.6.2
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