include/lttng/tp-mempool.h

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * lttng/tp-mempool.h
   4  *
   5  * Copyright (C) 2018 Julien Desfossez <jdesfossez@efficios.com>
   6  */
   7
   8 #ifndef LTTNG_TP_MEMPOOL_H
   9 #define LTTNG_TP_MEMPOOL_H
  10
  11 #include <linux/percpu.h>
  12
  13 #define LTTNG_TP_MEMPOOL_NR_BUF_PER_CPU 4
  14 #define LTTNG_TP_MEMPOOL_BUF_SIZE 4096
  15
  16 /*
  17  * Initialize the pool, only performed once. The pool is a set of
  18  * LTTNG_TP_MEMPOOL_NR_BUF_PER_CPU buffers of size LTTNG_TP_MEMPOOL_BUF_SIZE
  19  * per-cpu.
  20  *
  21  * Returns 0 on success, a negative value on error.
  22  */
  23 int lttng_tp_mempool_init(void);
  24
  25 /*
  26  * Destroy the pool and free all the memory allocated.
  27  */
  28 void lttng_tp_mempool_destroy(void);
  29
  30 /*
  31  * Ask for a buffer on the current cpu.
  32  *
  33  * The pool is per-cpu, but there is no exclusive access guarantee on the
  34  * per-cpu free-list, the caller needs to ensure it cannot get preempted or
  35  * interrupted while performing the allocation.
  36  *
  37  * The maximum size that can be allocated is LTTNG_TP_MEMPOOL_BUF_SIZE, and the
  38  * maximum number of buffers allocated simultaneously on the same CPU is
  39  * LTTNG_TP_MEMPOOL_NR_BUF_PER_CPU.
  40  *
  41  * Return a pointer to a buffer on success, NULL on error.
  42  */
  43 void *lttng_tp_mempool_alloc(size_t size);
  44
  45 /*
  46  * Release the memory reserved. Same concurrency limitations as the allocation.
  47  */
  48 void lttng_tp_mempool_free(void *ptr);
  49
  50 #endif /* LTTNG_TP_MEMPOOL_H */