[PATCH v4 1/6] eal: add thread attributes

[Tyler Retzlaff <roretzla@linux.microsoft.com>]

Implement thread attributes for:

    * thread affinity
    * thread priority

Implement functions for managing thread attributes.

  Priority is represented through an enum that allows for two levels:

    * RTE_THREAD_PRIORITY_NORMAL
    * RTE_THREAD_PRIORITY_REALTIME_CRITICAL

  Affinity is described by the rte_cpuset_t type.

An rte_thread_attr_t object can be set to the default values
by calling rte_thread_attr_init().

Signed-off-by: Narcisa Vasile <navasile@microsoft.com>
Signed-off-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
---
 lib/eal/common/meson.build   |  1 +
 lib/eal/common/rte_thread.c  | 60 ++++++++++++++++++++++++++++
 lib/eal/include/rte_thread.h | 93 ++++++++++++++++++++++++++++++++++++++++++++
 lib/eal/version.map          |  4 ++
 4 files changed, 158 insertions(+)
 create mode 100644 lib/eal/common/rte_thread.c

diff --git a/lib/eal/common/meson.build b/lib/eal/common/meson.build
index 917758c..1e77dba 100644
--- a/lib/eal/common/meson.build
+++ b/lib/eal/common/meson.build
@@ -36,6 +36,7 @@ sources += files(
         'rte_random.c',
         'rte_reciprocal.c',
         'rte_service.c',
+        'rte_thread.c',
         'rte_version.c',
 )
 if is_linux or is_windows
diff --git a/lib/eal/common/rte_thread.c b/lib/eal/common/rte_thread.c
new file mode 100644
index 0000000..d204cc5
--- /dev/null
+++ b/lib/eal/common/rte_thread.c
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright (C) 2022 Microsoft Corporation
+ */
+
+#include <rte_debug.h>
+#include <rte_thread.h>
+
+int
+rte_thread_attr_init(rte_thread_attr_t *attr)
+{
+	if (attr == NULL)
+		return EINVAL;
+
+	CPU_ZERO(&attr->cpuset);
+	attr->priority = RTE_THREAD_PRIORITY_NORMAL;
+
+	return 0;
+}
+
+int
+rte_thread_attr_set_affinity(rte_thread_attr_t *thread_attr,
+		rte_cpuset_t *cpuset)
+{
+	if (thread_attr == NULL)
+		return EINVAL;
+
+	if (cpuset == NULL)
+		return EINVAL;
+
+	thread_attr->cpuset = *cpuset;
+
+	return 0;
+}
+
+int
+rte_thread_attr_get_affinity(rte_thread_attr_t *thread_attr,
+		rte_cpuset_t *cpuset)
+{
+	if (thread_attr == NULL)
+		return EINVAL;
+
+	if (cpuset == NULL)
+		return EINVAL;
+
+	*cpuset = thread_attr->cpuset;
+
+	return 0;
+}
+
+int
+rte_thread_attr_set_priority(rte_thread_attr_t *thread_attr,
+		enum rte_thread_priority priority)
+{
+	if (thread_attr == NULL)
+		return EINVAL;
+
+	thread_attr->priority = priority;
+
+	return 0;
+}
diff --git a/lib/eal/include/rte_thread.h b/lib/eal/include/rte_thread.h
index 9e261bf..062308d 100644
--- a/lib/eal/include/rte_thread.h
+++ b/lib/eal/include/rte_thread.h
@@ -40,6 +40,18 @@ enum rte_thread_priority {
 	/**< highest thread priority allowed */
 };
 
+#ifdef RTE_HAS_CPUSET
+
+/**
+ * Representation for thread attributes.
+ */
+typedef struct {
+	enum rte_thread_priority priority; /**< thread priority */
+	rte_cpuset_t cpuset; /**< thread affinity */
+} rte_thread_attr_t;
+
+#endif /* RTE_HAS_CPUSET */
+
 /**
  * TLS key type, an opaque pointer.
  */
@@ -63,6 +75,87 @@ enum rte_thread_priority {
  * @warning
  * @b EXPERIMENTAL: this API may change without prior notice.
  *
+ * Initialize the attributes of a thread.
+ * These attributes can be passed to the rte_thread_create() function
+ * that will create a new thread and set its attributes according to attr.
+ *
+ * @param attr
+ *   Thread attributes to initialize.
+ *
+ * @return
+ *   On success, return 0.
+ *   On failure, return a positive errno-style error number.
+ */
+__rte_experimental
+int rte_thread_attr_init(rte_thread_attr_t *attr);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Set the CPU affinity value in the thread attributes pointed to
+ * by 'thread_attr'.
+ *
+ * @param thread_attr
+ *   Points to the thread attributes in which affinity will be updated.
+ *
+ * @param cpuset
+ *   Points to the value of the affinity to be set.
+ *
+ * @return
+ *   On success, return 0.
+ *   On failure, return a positive errno-style error number.
+ */
+__rte_experimental
+int rte_thread_attr_set_affinity(rte_thread_attr_t *thread_attr,
+		rte_cpuset_t *cpuset);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Get the value of CPU affinity that is set in the thread attributes pointed
+ * to by 'thread_attr'.
+ *
+ * @param thread_attr
+ *   Points to the thread attributes from which affinity will be retrieved.
+ *
+ * @param cpuset
+ *   Pointer to the memory that will store the affinity.
+ *
+ * @return
+ *   On success, return 0.
+ *   On failure, return a positive errno-style error number.
+ */
+__rte_experimental
+int rte_thread_attr_get_affinity(rte_thread_attr_t *thread_attr,
+		rte_cpuset_t *cpuset);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Set the thread priority value in the thread attributes pointed to
+ * by 'thread_attr'.
+ *
+ * @param thread_attr
+ *   Points to the thread attributes in which priority will be updated.
+ *
+ * @param priority
+ *   Points to the value of the priority to be set.
+ *
+ * @return
+ *   On success, return 0.
+ *   On failure, return a positive errno-style error number.
+ */
+__rte_experimental
+int rte_thread_attr_set_priority(rte_thread_attr_t *thread_attr,
+		enum rte_thread_priority priority);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
  * Set the affinity of thread 'thread_id' to the cpu set
  * specified by 'cpuset'.
  *
diff --git a/lib/eal/version.map b/lib/eal/version.map
index c2a2ceb..6d8f89a 100644
--- a/lib/eal/version.map
+++ b/lib/eal/version.map
@@ -419,6 +419,10 @@ EXPERIMENTAL {
 
 	# added in 22.07
 	rte_drand;
+	rte_thread_attr_get_affinity;
+	rte_thread_attr_init;
+	rte_thread_attr_set_affinity;
+	rte_thread_attr_set_priority;
 	rte_thread_get_affinity_by_id;
 	rte_thread_get_priority;
 	rte_thread_self;
-- 
1.8.3.1