lttng-tp-mempool.h

   1 #ifndef LTTNG_TP_MEMPOOL_H
   2 #define LTTNG_TP_MEMPOOL_H
   3
   4 /*
   5  * lttng-tp-mempool.h
   6  *
   7  * Copyright (C) 2018 Julien Desfossez <jdesfossez@efficios.com>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; only
  12  * version 2.1 of the License.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #include <linux/percpu.h>
  25
  26 #define LTTNG_TP_MEMPOOL_NR_BUF_PER_CPU 4
  27 #define LTTNG_TP_MEMPOOL_BUF_SIZE 4096
  28
  29 /*
  30  * Initialize the pool, only performed once. The pool is a set of
  31  * LTTNG_TP_MEMPOOL_NR_BUF_PER_CPU buffers of size LTTNG_TP_MEMPOOL_BUF_SIZE
  32  * per-cpu.
  33  *
  34  * Returns 0 on success, a negative value on error.
  35  */
  36 int lttng_tp_mempool_init(void);
  37
  38 /*
  39  * Destroy the pool and free all the memory allocated.
  40  */
  41 void lttng_tp_mempool_destroy(void);
  42
  43 /*
  44  * Ask for a buffer on the current cpu.
  45  *
  46  * The pool is per-cpu, but there is no exclusive access guarantee on the
  47  * per-cpu free-list, the caller needs to ensure it cannot get preempted or
  48  * interrupted while performing the allocation.
  49  *
  50  * The maximum size that can be allocated is LTTNG_TP_MEMPOOL_BUF_SIZE, and the
  51  * maximum number of buffers allocated simultaneously on the same CPU is
  52  * LTTNG_TP_MEMPOOL_NR_BUF_PER_CPU.
  53  *
  54  * Return a pointer to a buffer on success, NULL on error.
  55  */
  56 void *lttng_tp_mempool_alloc(size_t size);
  57
  58 /*
  59  * Release the memory reserved. Same concurrency limitations as the allocation.
  60  */
  61 void lttng_tp_mempool_free(void *ptr);
  62
  63 #endif /* LTTNG_TP_MEMPOOL_H */