Subversion Repositories HelenOS

/*

 * Copyright (C) 2006 Ondrej Palkovsky

 * 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.

 */

#include <synch/spinlock.h>

#include <mm/slab.h>

#include <list.h>

#include <memstr.h>

#include <align.h>

#include <mm/heap.h>

#include <mm/frame.h>

#include <config.h>

#include <print.h>

#include <arch.h>

#include <panic.h>

#include <debug.h>

SPINLOCK_INITIALIZE(slab_cache_lock);

LIST_INITIALIZE(slab_cache_list);

slab_cache_t mag_cache;

typedef struct {

    slab_cache_t *cache; /**< Pointer to parent cache */

    link_t link;       /* List of full/partial slabs */

    void *start;       /**< Start address of first available item */

    count_t available; /**< Count of available items in this slab */

    index_t nextavail; /**< The index of next available item */

}slab_t;

/**************************************/

/* SLAB allocation functions          */

/**

 * Allocate frames for slab space and initialize

 *

 * TODO: Change slab_t allocation to slab_alloc(????), malloc with flags!!

 */

static slab_t * slab_space_alloc(slab_cache_t *cache, int flags)

{

    void *data;

    slab_t *slab;

    size_t fsize;

    int i;

    zone_t *zone = NULL;

    int status;

    frame_t *frame;

    data = (void *)frame_alloc(FRAME_KA | flags, cache->order, &status, &zone);

    if (status != FRAME_OK) {

        return NULL;

    }

    if (! cache->flags & SLAB_CACHE_SLINSIDE) {

        slab = malloc(sizeof(*slab)); // , flags);

        if (!slab) {

            frame_free((__address)data);

            return NULL;

        }

    } else {

        fsize = (PAGE_SIZE << cache->order);

        slab = data + fsize - sizeof(*slab);

    }

    /* Fill in slab structures */

    /* TODO: some better way of accessing the frame */

    for (i=0; i< (1<<cache->order); i++) {

        frame = ADDR2FRAME(zone, KA2PA((__address)(data+i*PAGE_SIZE)));

        frame->parent = slab;

    }

    slab->start = data;

    slab->available = cache->objects;

    slab->nextavail = 0;

    for (i=0; i<cache->objects;i++)

        *((int *) (slab->start + i*cache->size)) = i+1;

    atomic_inc(&cache->allocated_slabs);

    return slab;

}

/**

 * Free space associated with SLAB

 *

 * @return number of freed frames

 */

static count_t slab_space_free(slab_cache_t *cache, slab_t *slab)

{

    frame_free((__address)slab->start);

    if (! cache->flags & SLAB_CACHE_SLINSIDE)

        free(slab);

    atomic_dec(&cache->allocated_slabs);

    return 1 << cache->order;

}

/** Map object to slab structure */

static slab_t * obj2slab(void *obj)

{

    frame_t *frame;

    frame = frame_addr2frame((__address)obj);

    return (slab_t *)frame->parent;

}

/**************************************/

/* SLAB functions */

/**

 * Return object to slab and call a destructor

 *

 * Assume the cache->lock is held;

 *

 * @param slab If the caller knows directly slab of the object, otherwise NULL

 *

 * @return Number of freed pages

 */

static count_t slab_obj_destroy(slab_cache_t *cache, void *obj,

                slab_t *slab)

{

    count_t frames = 0;

    if (!slab)

        slab = obj2slab(obj);

    spinlock_lock(&cache->lock);

    *((int *)obj) = slab->nextavail;

    slab->nextavail = (obj - slab->start)/cache->size;

    slab->available++;

    /* Move it to correct list */

    if (slab->available == 1) {

        /* It was in full, move to partial */

        list_remove(&slab->link);

        list_prepend(&slab->link, &cache->partial_slabs);

    }

    if (slab->available == cache->objects) {

        /* Free associated memory */

        list_remove(&slab->link);

        /* Avoid deadlock */

        spinlock_unlock(&cache->lock);

        frames = slab_space_free(cache, slab);

        spinlock_lock(&cache->lock);

    }

    spinlock_unlock(&cache->lock);

    return frames;

}

/**

 * Take new object from slab or create new if needed

 *

 * Assume cache->lock is held.

 *

 * @return Object address or null

 */

static void * slab_obj_create(slab_cache_t *cache, int flags)

{

    slab_t *slab;

    void *obj;

    if (list_empty(&cache->partial_slabs)) {

        /* Allow recursion and reclaiming

         * - this should work, as the SLAB control structures

         *   are small and do not need to allocte with anything

         *   other ten frame_alloc when they are allocating,

         *   that's why we should get recursion at most 1-level deep

         */

        spinlock_unlock(&cache->lock);

        slab = slab_space_alloc(cache, flags);

        spinlock_lock(&cache->lock);

        if (!slab) {

            return NULL;

        }

    } else {

        slab = list_get_instance(cache->partial_slabs.next,

                     slab_t,

                     link);

        list_remove(&slab->link);

    }

    obj = slab->start + slab->nextavail * cache->size;

    slab->nextavail = *((int *)obj);

    slab->available--;

    if (! slab->available)

        list_prepend(&slab->link, &cache->full_slabs);

    else

        list_prepend(&slab->link, &cache->partial_slabs);

    return obj;

}

/**************************************/

/* CPU-Cache slab functions */

/**

 * Free all objects in magazine and free memory associated with magazine

 *

 * Assume mag_cache[cpu].lock is locked

 *

 * @return Number of freed pages

 */

static count_t magazine_destroy(slab_cache_t *cache,

                slab_magazine_t *mag)

{

    int i;

    count_t frames = 0;

    for (i=0;i < mag->busy; i++)

        frames += slab_obj_destroy(cache, mag->objs[i], NULL);

    slab_free(&mag_cache, mag);

    return frames;

}

/**

 * Try to find object in CPU-cache magazines

 *

 * @return Pointer to object or NULL if not available

 */

static void * magazine_obj_get(slab_cache_t *cache)

{

    slab_magazine_t *mag;

    spinlock_lock(&cache->mag_cache[CPU->id].lock);

    mag = cache->mag_cache[CPU->id].current;

    if (!mag)

        goto out;

    if (!mag->busy) {

        /* If current is empty && last exists && not empty, exchange */

        if (cache->mag_cache[CPU->id].last \

            && cache->mag_cache[CPU->id].last->busy) {

            cache->mag_cache[CPU->id].current = cache->mag_cache[CPU->id].last;

            cache->mag_cache[CPU->id].last = mag;

            mag = cache->mag_cache[CPU->id].current;

            goto gotit;

        }

        /* If still not busy, exchange current with some from

         * other full magazines */

        spinlock_lock(&cache->lock);

        if (list_empty(&cache->magazines)) {

            spinlock_unlock(&cache->lock);

            goto out;

        }

        /* Free current magazine and take one from list */

        slab_free(&mag_cache, mag);

        mag = list_get_instance(cache->magazines.next,

                    slab_magazine_t,

                    link);

        list_remove(&mag->link);

        spinlock_unlock(&cache->lock);

    }

gotit:

    spinlock_unlock(&cache->mag_cache[CPU->id].lock);

    return mag->objs[--mag->busy];

out:   

    spinlock_unlock(&cache->mag_cache[CPU->id].lock);

    return NULL;

}

/**

 * Put object into CPU-cache magazine

 *

 * We have 2 magazines bound to processor.

 * First try the current.

 *  If full, try the last.

 *   If full, put to magazines list.

 *   allocate new, exchange last & current

 *

 * @return 0 - success, -1 - could not get memory

 */

static int magazine_obj_put(slab_cache_t *cache, void *obj)

{

    slab_magazine_t *mag;

    spinlock_lock(&cache->mag_cache[CPU->id].lock);

    mag = cache->mag_cache[CPU->id].current;

    if (!mag) {

        /* We do not want to sleep just because of caching */

        /* Especially we do not want reclaiming to start, as

         * this would deadlock */

        mag = slab_alloc(&mag_cache, FRAME_ATOMIC | FRAME_NO_RECLAIM);

        if (!mag) /* Allocation failed, give up on caching */

            goto errout;

        cache->mag_cache[CPU->id].current = mag;

        mag->size = SLAB_MAG_SIZE;

        mag->busy = 0;

    } else if (mag->busy == mag->size) {

        /* If the last is full | empty, allocate new */

        mag = cache->mag_cache[CPU->id].last;

        if (!mag || mag->size == mag->busy) {

            if (mag)

                list_prepend(&mag->link, &cache->magazines);

            mag = slab_alloc(&mag_cache, FRAME_ATOMIC | FRAME_NO_RECLAIM);

            if (!mag)

                goto errout;

            mag->size = SLAB_MAG_SIZE;

            mag->busy = 0;

            cache->mag_cache[CPU->id].last = mag;

        }

        /* Exchange the 2 */

        cache->mag_cache[CPU->id].last = cache->mag_cache[CPU->id].current;

        cache->mag_cache[CPU->id].current = mag;

    }

    mag->objs[mag->busy++] = obj;

    spinlock_unlock(&cache->mag_cache[CPU->id].lock);

    return 0;

errout:

    spinlock_unlock(&cache->mag_cache[CPU->id].lock);

    return -1;

}

/**************************************/

/* SLAB CACHE functions */

/** Return number of objects that fit in certain cache size */

static int comp_objects(slab_cache_t *cache)

{

    if (cache->flags & SLAB_CACHE_SLINSIDE)

        return ((PAGE_SIZE << cache->order) - sizeof(slab_t)) / cache->size;

    else

        return (PAGE_SIZE << cache->order) / cache->size;

}

/** Return wasted space in slab */

static int badness(slab_cache_t *cache)

{

    int objects;

    int ssize;

    objects = comp_objects(cache);

    ssize = PAGE_SIZE << cache->order;

    if (cache->flags & SLAB_CACHE_SLINSIDE)

        ssize -= sizeof(slab_t);

    return ssize - objects*cache->size;

}

/** Initialize allocated memory as a slab cache */

static void

_slab_cache_create(slab_cache_t *cache,

           char *name,

           size_t size,

           size_t align,

           int (*constructor)(void *obj, int kmflag),

           void (*destructor)(void *obj),

           int flags)

{

    int i;

    memsetb((__address)cache, sizeof(*cache), 0);

    cache->name = name;

    if (align)

        size = ALIGN_UP(size, align);

    cache->size = size;

    cache->constructor = constructor;

    cache->destructor = destructor;

    cache->flags = flags;

    list_initialize(&cache->full_slabs);

    list_initialize(&cache->partial_slabs);

    list_initialize(&cache->magazines);

    spinlock_initialize(&cache->lock, "cachelock");

    if (! cache->flags & SLAB_CACHE_NOMAGAZINE) {

        for (i=0; i< config.cpu_count; i++)

            spinlock_initialize(&cache->mag_cache[i].lock,

                        "cpucachelock");

    }

    /* Compute slab sizes, object counts in slabs etc. */

    if (cache->size < SLAB_INSIDE_SIZE)

        cache->flags |= SLAB_CACHE_SLINSIDE;

    /* Minimum slab order */

    cache->order = (cache->size / PAGE_SIZE) + 1;

    while (badness(cache) > SLAB_MAX_BADNESS(cache)) {

        cache->order += 1;

    }

    cache->objects = comp_objects(cache);

    spinlock_lock(&slab_cache_lock);

    list_append(&cache->link, &slab_cache_list);

    spinlock_unlock(&slab_cache_lock);

}

/** Create slab cache  */

slab_cache_t * slab_cache_create(char *name,

                 size_t size,

                 size_t align,

                 int (*constructor)(void *obj, int kmflag),

                 void (*destructor)(void *obj),

                 int flags)

{

    slab_cache_t *cache;

    cache = malloc(sizeof(*cache) + config.cpu_count*sizeof(cache->mag_cache[0]));

    _slab_cache_create(cache, name, size, align, constructor, destructor,

               flags);

    return cache;

}

/**

 * Reclaim space occupied by objects that are already free

 *

 * @param flags If contains SLAB_RECLAIM_ALL, do aggressive freeing

 * @return Number of freed pages

 *

 * TODO: Add light reclaim

 */

static count_t _slab_reclaim(slab_cache_t *cache, int flags)

{

    int i;

    slab_magazine_t *mag;

    link_t *cur;

    count_t frames = 0;

    if (cache->flags & SLAB_CACHE_NOMAGAZINE)

        return 0; /* Nothing to do */

    /* First lock all cpu caches, then the complete cache lock */

    for (i=0; i < config.cpu_count; i++)

        spinlock_lock(&cache->mag_cache[i].lock);

    spinlock_lock(&cache->lock);

    if (flags & SLAB_RECLAIM_ALL) {

        /* Aggressive memfree */

        /* Destroy CPU magazines */

        for (i=0; i<config.cpu_count; i++) {

            mag = cache->mag_cache[i].current;

            if (mag)

                frames += magazine_destroy(cache, mag);

            cache->mag_cache[i].current = NULL;

            mag = cache->mag_cache[i].last;

            if (mag)

                frames += magazine_destroy(cache, mag);

            cache->mag_cache[i].last = NULL;

        }

    }

    /* Destroy full magazines */

    cur=cache->magazines.prev;

    while (cur!=&cache->magazines) {

        mag = list_get_instance(cur, slab_magazine_t, link);

        cur = cur->prev;

        list_remove(cur->next);

        frames += magazine_destroy(cache,mag);

        /* If we do not do full reclaim, break

         * as soon as something is freed */

        if (!(flags & SLAB_RECLAIM_ALL) && frames)

            break;

    }

    spinlock_unlock(&cache->lock);

    for (i=0; i < config.cpu_count; i++)

        spinlock_unlock(&cache->mag_cache[i].lock);

    return frames;

}

/** Check that there are no slabs and remove cache from system  */

void slab_cache_destroy(slab_cache_t *cache)

{

    /* Do not lock anything, we assume the software is correct and

     * does not touch the cache when it decides to destroy it */

    /* Destroy all magazines */

    _slab_reclaim(cache, SLAB_RECLAIM_ALL);

    /* All slabs must be empty */

    if (!list_empty(&cache->full_slabs) \

        || !list_empty(&cache->partial_slabs))

        panic("Destroying cache that is not empty.");

    spinlock_lock(&slab_cache_lock);

    list_remove(&cache->link);

    spinlock_unlock(&slab_cache_lock);

    free(cache);

}

/** Allocate new object from cache - if no flags given, always returns

    memory */

void * slab_alloc(slab_cache_t *cache, int flags)

{

    ipl_t ipl;

    void *result = NULL;

    /* Disable interrupts to avoid deadlocks with interrupt handlers */

    ipl = interrupts_disable();

    if (!cache->flags & SLAB_CACHE_NOMAGAZINE)

        result = magazine_obj_get(cache);

    if (!result) {

        spinlock_lock(&cache->lock);

        result = slab_obj_create(cache, flags);

        spinlock_unlock(&cache->lock);

    }

    if (result)

        atomic_inc(&cache->allocated_objs);

    interrupts_restore(ipl);

    return result;

}

/** Return object to cache  */

void slab_free(slab_cache_t *cache, void *obj)

{

    ipl_t ipl;

    ipl = interrupts_disable();

    if ((cache->flags & SLAB_CACHE_NOMAGAZINE) \

        || magazine_obj_put(cache, obj)) {

        spinlock_lock(&cache->lock);

        slab_obj_destroy(cache, obj, NULL);

        spinlock_unlock(&cache->lock);

    }

    atomic_dec(&cache->allocated_objs);

    interrupts_restore(ipl);

}

/* Go through all caches and reclaim what is possible */

count_t slab_reclaim(int flags)

{

    slab_cache_t *cache;

    link_t *cur;

    count_t frames = 0;

    spinlock_lock(&slab_cache_lock);

    for (cur = slab_cache_list.next;cur!=&slab_cache_list; cur=cur->next) {

        cache = list_get_instance(cur, slab_cache_t, link);

        frames += _slab_reclaim(cache, flags);

    }

    spinlock_unlock(&slab_cache_lock);

    return frames;

}

/* Print list of slabs */

void slab_print_list(void)

{

    slab_cache_t *cache;

    link_t *cur;

    spinlock_lock(&slab_cache_lock);

    printf("SLAB name\tOsize\tOrder\tOcnt\tSlabs\tAllocobjs\n");

    for (cur = slab_cache_list.next;cur!=&slab_cache_list; cur=cur->next) {

        cache = list_get_instance(cur, slab_cache_t, link);

        printf("%s\t%d\t%d\t%d\t%d\t%d\n", cache->name, cache->size,

               cache->order, cache->objects,

               atomic_get(&cache->allocated_slabs),

               atomic_get(&cache->allocated_objs));

    }

    spinlock_unlock(&slab_cache_lock);

}

void slab_cache_init(void)

{

    /* Initialize magazine cache */

    _slab_cache_create(&mag_cache,

               "slab_magazine",

               sizeof(slab_magazine_t)+SLAB_MAG_SIZE*sizeof(void*),

               sizeof(__address),

               NULL, NULL,

               SLAB_CACHE_NOMAGAZINE);

    /* Initialize structures for malloc */

}