Cleanup: Move headers from toplevel to include/lttng/

[lttng-modules.git] / include / lttng / tp-mempool.h

diff --git a/include/lttng/tp-mempool.h b/include/lttng/tp-mempool.h
new file mode 100644 (file)
index 0000000..587e9bd
--- /dev/null
+++ b/include/lttng/tp-mempool.h
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
+ *
+ * lttng/tp-mempool.h
+ *
+ * Copyright (C) 2018 Julien Desfossez <jdesfossez@efficios.com>
+ */
+
+#ifndef LTTNG_TP_MEMPOOL_H
+#define LTTNG_TP_MEMPOOL_H
+
+#include <linux/percpu.h>
+
+#define LTTNG_TP_MEMPOOL_NR_BUF_PER_CPU 4
+#define LTTNG_TP_MEMPOOL_BUF_SIZE 4096
+
+/*
+ * Initialize the pool, only performed once. The pool is a set of
+ * LTTNG_TP_MEMPOOL_NR_BUF_PER_CPU buffers of size LTTNG_TP_MEMPOOL_BUF_SIZE
+ * per-cpu.
+ *
+ * Returns 0 on success, a negative value on error.
+ */
+int lttng_tp_mempool_init(void);
+
+/*
+ * Destroy the pool and free all the memory allocated.
+ */
+void lttng_tp_mempool_destroy(void);
+
+/*
+ * Ask for a buffer on the current cpu.
+ *
+ * The pool is per-cpu, but there is no exclusive access guarantee on the
+ * per-cpu free-list, the caller needs to ensure it cannot get preempted or
+ * interrupted while performing the allocation.
+ *
+ * The maximum size that can be allocated is LTTNG_TP_MEMPOOL_BUF_SIZE, and the
+ * maximum number of buffers allocated simultaneously on the same CPU is
+ * LTTNG_TP_MEMPOOL_NR_BUF_PER_CPU.
+ *
+ * Return a pointer to a buffer on success, NULL on error.
+ */
+void *lttng_tp_mempool_alloc(size_t size);
+
+/*
+ * Release the memory reserved. Same concurrency limitations as the allocation.
+ */
+void lttng_tp_mempool_free(void *ptr);
+
+#endif /* LTTNG_TP_MEMPOOL_H */