/* * Copyright (c) 2011 Jakub Jermar * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * - Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * - The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /** @addtogroup kernel_generic_mm * @{ */ /** * @file * @brief Memory reservations. */ #include <assert.h> #include <mm/reserve.h> #include <mm/frame.h> #include <mm/slab.h> #include <synch/spinlock.h> #include <typedefs.h> #include <arch/types.h> static bool reserve_initialized = false; IRQ_SPINLOCK_STATIC_INITIALIZE_NAME(reserve_lock, "reserve_lock"); static ssize_t reserve = 0; /** Initialize memory reservations tracking. * * This function must be called after frame zones are created and merged * and before any address space area is created. */ void reserve_init(void) { reserve = frame_total_free_get(); reserve_initialized = true; } /** Try to reserve memory. * * This function may not be called from contexts that do not allow memory * reclaiming, such as some invocations of frame_alloc_generic(). * * @param size Number of frames to reserve. * @return True on success or false otherwise. */ bool reserve_try_alloc(size_t size) { bool reserved = false; assert(reserve_initialized); irq_spinlock_lock(&reserve_lock, true); if (reserve >= 0 && (size_t) reserve >= size) { reserve -= size; reserved = true; } else { /* * Some reservable frames may be cached by the slab allocator. * Try to reclaim some reservable memory. Try to be gentle for * the first time. If it does not help, try to reclaim * everything. */ irq_spinlock_unlock(&reserve_lock, true); slab_reclaim(0); irq_spinlock_lock(&reserve_lock, true); if (reserve >= 0 && (size_t) reserve >= size) { reserve -= size; reserved = true; } else { irq_spinlock_unlock(&reserve_lock, true); slab_reclaim(SLAB_RECLAIM_ALL); irq_spinlock_lock(&reserve_lock, true); if (reserve >= 0 && (size_t) reserve >= size) { reserve -= size; reserved = true; } } } irq_spinlock_unlock(&reserve_lock, true); return reserved; } /** Reserve memory. * * This function simply marks the respective amount of memory frames reserved. * It does not implement any sort of blocking for the case there is not enough * reservable memory. It will simply take the reserve into negative numbers and * leave the blocking up to the allocation phase. * * @param size Number of frames to reserve. */ void reserve_force_alloc(size_t size) { if (!reserve_initialized) return; irq_spinlock_lock(&reserve_lock, true); reserve -= size; irq_spinlock_unlock(&reserve_lock, true); } /** Unreserve memory. * * @param size Number of frames to unreserve. */ void reserve_free(size_t size) { if (!reserve_initialized) return; irq_spinlock_lock(&reserve_lock, true); reserve += size; irq_spinlock_unlock(&reserve_lock, true); } /** @} */