WebSVN – HelenOS – Diff – /branches/dd/kernel/generic/src/mm/slab.c


/*
 * 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.
 */
 
/** @addtogroup genericmm
 * @{
 */
 
/**
 * @file
 * @brief   Slab allocator.
 *
 * The slab allocator is closely modelled after OpenSolaris slab allocator.
 * @see http://www.usenix.org/events/usenix01/full_papers/bonwick/bonwick_html/
 *
 * with the following exceptions:
 * @li empty slabs are deallocated immediately
 *     (in Linux they are kept in linked list, in Solaris ???)
 * @li empty magazines are deallocated when not needed
 *     (in Solaris they are held in linked list in slab cache)
 *
 * Following features are not currently supported but would be easy to do:
 * @li cache coloring
 * @li dynamic magazine growing (different magazine sizes are already
 *     supported, but we would need to adjust allocation strategy)
 *
 * The slab allocator supports per-CPU caches ('magazines') to facilitate
 * good SMP scaling.
 *
 * When a new object is being allocated, it is first checked, if it is
 * available in a CPU-bound magazine. If it is not found there, it is
 * allocated from a CPU-shared slab - if a partially full one is found,
 * it is used, otherwise a new one is allocated.
 *
 * When an object is being deallocated, it is put to a CPU-bound magazine.
 * If there is no such magazine, a new one is allocated (if this fails,
 * the object is deallocated into slab). If the magazine is full, it is
 * put into cpu-shared list of magazines and a new one is allocated.
 *
 * The CPU-bound magazine is actually a pair of magazines in order to avoid
 * thrashing when somebody is allocating/deallocating 1 item at the magazine
 * size boundary. LIFO order is enforced, which should avoid fragmentation
 * as much as possible.
 *  
 * Every cache contains list of full slabs and list of partially full slabs.
 * Empty slabs are immediately freed (thrashing will be avoided because
 * of magazines).
 *
 * The slab information structure is kept inside the data area, if possible.
 * The cache can be marked that it should not use magazines. This is used
 * only for slab related caches to avoid deadlocks and infinite recursion
 * (the slab allocator uses itself for allocating all it's control structures).
 *
 * The slab allocator allocates a lot of space and does not free it. When
 * the frame allocator fails to allocate a frame, it calls slab_reclaim().
 * It tries 'light reclaim' first, then brutal reclaim. The light reclaim
 * releases slabs from cpu-shared magazine-list, until at least 1 slab
 * is deallocated in each cache (this algorithm should probably change).
 * The brutal reclaim removes all cached objects, even from CPU-bound
 * magazines.
 *
 * @todo
 * For better CPU-scaling the magazine allocation strategy should
 * be extended. Currently, if the cache does not have magazine, it asks
 * for non-cpu cached magazine cache to provide one. It might be feasible
 * to add cpu-cached magazine cache (which would allocate it's magazines
 * from non-cpu-cached mag. cache). This would provide a nice per-cpu
 * buffer. The other possibility is to use the per-cache
 * 'empty-magazine-list', which decreases competing for 1 per-system
 * magazine cache.
 *
 * @todo
 * it might be good to add granularity of locks even to slab level,
 * we could then try_spinlock over all partial slabs and thus improve
 * scalability even on slab level
 */
 
#include <synch/spinlock.h>
#include <mm/slab.h>
#include <adt/list.h>
#include <memstr.h>
#include <align.h>
#include <mm/frame.h>
#include <config.h>
#include <print.h>
#include <arch.h>
#include <panic.h>
#include <debug.h>
#include <bitops.h>
#include <macros.h>
 
SPINLOCK_INITIALIZE(slab_cache_lock);
static LIST_INITIALIZE(slab_cache_list);
 
/** Magazine cache */
static slab_cache_t mag_cache;
/** Cache for cache descriptors */
static slab_cache_t slab_cache_cache;
/** Cache for external slab descriptors
 * This time we want per-cpu cache, so do not make it static
 * - using slab for internal slab structures will not deadlock,
 *   as all slab structures are 'small' - control structures of
 *   their caches do not require further allocation
 */
static slab_cache_t *slab_extern_cache;
/** Caches for malloc */
static slab_cache_t *malloc_caches[SLAB_MAX_MALLOC_W - SLAB_MIN_MALLOC_W + 1];
static char *malloc_names[] =  {
    "malloc-16",
    "malloc-32",
    "malloc-64",
    "malloc-128",
    "malloc-256",
    "malloc-512",
    "malloc-1K",
    "malloc-2K",
    "malloc-4K",
    "malloc-8K",
    "malloc-16K",
    "malloc-32K",
    "malloc-64K",
    "malloc-128K",
    "malloc-256K",
    "malloc-512K",
    "malloc-1M",
    "malloc-2M",
    "malloc-4M"
};
 
/** Slab descriptor */
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;
 
#ifdef CONFIG_DEBUG
static int _slab_initialized = 0;
#endif
 
/**************************************/
/* Slab allocation functions          */
 
/**
 * Allocate frames for slab space and initialize
 *
 */
static slab_t *slab_space_alloc(slab_cache_t *cache, int flags)
{
    void *data;
    slab_t *slab;
    size_t fsize;
    unsigned int i;
    count_t zone = 0;
   
    data = frame_alloc_generic(cache->order, FRAME_KA | flags, &zone);
    if (!data) {
        return NULL;
    }
    if (!(cache->flags & SLAB_CACHE_SLINSIDE)) {
        slab = slab_alloc(slab_extern_cache, flags);
        if (!slab) {
            frame_free(KA2PA(data));
            return NULL;
        }
    } else {
        fsize = (PAGE_SIZE << cache->order);
        slab = data + fsize - sizeof(*slab);
    }
   
    /* Fill in slab structures */
    for (i = 0; i < ((unsigned int) 1 << cache->order); i++)
        frame_set_parent(ADDR2PFN(KA2PA(data)) + i, slab, zone);
 
    slab->start = data;
    slab->available = cache->objects;
    slab->nextavail = 0;
    slab->cache = cache;
 
    for (i = 0; i < cache->objects; i++)
        *((int *) (slab->start + i*cache->size)) = i + 1;
 
    atomic_inc(&cache->allocated_slabs);
    return slab;
}
 
/**
 * Deallocate space associated with slab
 *
 * @return number of freed frames
 */
static count_t slab_space_free(slab_cache_t *cache, slab_t *slab)
{
    frame_free(KA2PA(slab->start));
    if (! (cache->flags & SLAB_CACHE_SLINSIDE))
        slab_free(slab_extern_cache, slab);
 
    atomic_dec(&cache->allocated_slabs);
   
    return 1 << cache->order;
}
 
/** Map object to slab structure */
static slab_t * obj2slab(void *obj)
{
    return (slab_t *) frame_get_parent(ADDR2PFN(KA2PA(obj)), 0);
}
 
/**************************************/
/* Slab functions */
 
 
/**
 * Return object to slab and call a destructor
 *
 * @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)
{
    int freed = 0;
 
    if (!slab)
        slab = obj2slab(obj);
 
    ASSERT(slab->cache == cache);
 
    if (cache->destructor)
        freed = cache->destructor(obj);
   
    spinlock_lock(&cache->slablock);
    ASSERT(slab->available < cache->objects);
 
    *((int *)obj) = slab->nextavail;
    slab->nextavail = (obj - slab->start) / cache->size;
    slab->available++;
 
    /* Move it to correct list */
    if (slab->available == cache->objects) {
        /* Free associated memory */
        list_remove(&slab->link);
        spinlock_unlock(&cache->slablock);
 
        return freed + slab_space_free(cache, slab);
 
    } else if (slab->available == 1) {
        /* It was in full, move to partial */
        list_remove(&slab->link);
        list_prepend(&slab->link, &cache->partial_slabs);
    }
    spinlock_unlock(&cache->slablock);
    return freed;
}
 
/**
 * Take new object from slab or create new if needed
 *
 * @return Object address or null
 */
static void *slab_obj_create(slab_cache_t *cache, int flags)
{
    slab_t *slab;
    void *obj;
 
    spinlock_lock(&cache->slablock);
 
    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 allocate with anything
         *   other than frame_alloc when they are allocating,
         *   that's why we should get recursion at most 1-level deep
         */
        spinlock_unlock(&cache->slablock);
        slab = slab_space_alloc(cache, flags);
        if (!slab)
            return NULL;
        spinlock_lock(&cache->slablock);
    } 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);
 
    spinlock_unlock(&cache->slablock);
 
    if (cache->constructor && cache->constructor(obj, flags)) {
        /* Bad, bad, construction failed */
        slab_obj_destroy(cache, obj, slab);
        return NULL;
    }
    return obj;
}
 
/**************************************/
/* CPU-Cache slab functions */
 
/**
 * Finds a full magazine in cache, takes it from list
 * and returns it
 *
 * @param first If true, return first, else last mag
 */
static slab_magazine_t *get_mag_from_cache(slab_cache_t *cache, int first)
{
    slab_magazine_t *mag = NULL;
    link_t *cur;
 
    spinlock_lock(&cache->maglock);
    if (!list_empty(&cache->magazines)) {
        if (first)
            cur = cache->magazines.next;
        else
            cur = cache->magazines.prev;
        mag = list_get_instance(cur, slab_magazine_t, link);
        list_remove(&mag->link);
        atomic_dec(&cache->magazine_counter);
    }
    spinlock_unlock(&cache->maglock);
    return mag;
}
 
/** Prepend magazine to magazine list in cache */
static void put_mag_to_cache(slab_cache_t *cache, slab_magazine_t *mag)
{
    spinlock_lock(&cache->maglock);
 
    list_prepend(&mag->link, &cache->magazines);
    atomic_inc(&cache->magazine_counter);
   
    spinlock_unlock(&cache->maglock);
}
 
/**
 * Free all objects in magazine and free memory associated with magazine
 *
 * @return Number of freed pages
 */
static count_t magazine_destroy(slab_cache_t *cache, slab_magazine_t *mag)
{
    unsigned int i;
    count_t frames = 0;
 
    for (i = 0; i < mag->busy; i++) {
        frames += slab_obj_destroy(cache, mag->objs[i], NULL);
        atomic_dec(&cache->cached_objs);
    }
   
    slab_free(&mag_cache, mag);
 
    return frames;
}
 
/**
 * Find full magazine, set it as current and return it
 *
 * Assume cpu_magazine lock is held
 */
static slab_magazine_t *get_full_current_mag(slab_cache_t *cache)
{
    slab_magazine_t *cmag, *lastmag, *newmag;
 
    cmag = cache->mag_cache[CPU->id].current;
    lastmag = cache->mag_cache[CPU->id].last;
    if (cmag) { /* First try local CPU magazines */
        if (cmag->busy)
            return cmag;
 
        if (lastmag && lastmag->busy) {
            cache->mag_cache[CPU->id].current = lastmag;
            cache->mag_cache[CPU->id].last = cmag;
            return lastmag;
        }
    }
    /* Local magazines are empty, import one from magazine list */
    newmag = get_mag_from_cache(cache, 1);
    if (!newmag)
        return NULL;
 
    if (lastmag)
        magazine_destroy(cache, lastmag);
 
    cache->mag_cache[CPU->id].last = cmag;
    cache->mag_cache[CPU->id].current = newmag;
    return newmag;
}
 
/**
 * 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;
    void *obj;
 
    if (!CPU)
        return NULL;
 
    spinlock_lock(&cache->mag_cache[CPU->id].lock);
 
    mag = get_full_current_mag(cache);
    if (!mag) {
        spinlock_unlock(&cache->mag_cache[CPU->id].lock);
        return NULL;
    }
    obj = mag->objs[--mag->busy];
    spinlock_unlock(&cache->mag_cache[CPU->id].lock);
    atomic_dec(&cache->cached_objs);
   
    return obj;
}
 
/**
 * Assure that the current magazine is empty, return pointer to it, or NULL if
 * no empty magazine is available and cannot be allocated
 *
 * Assume mag_cache[CPU->id].lock is held
 *
 * 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
 *
 */
static slab_magazine_t *make_empty_current_mag(slab_cache_t *cache)
{
    slab_magazine_t *cmag,*lastmag,*newmag;
 
    cmag = cache->mag_cache[CPU->id].current;
    lastmag = cache->mag_cache[CPU->id].last;
 
    if (cmag) {
        if (cmag->busy < cmag->size)
            return cmag;
        if (lastmag && lastmag->busy < lastmag->size) {
            cache->mag_cache[CPU->id].last = cmag;
            cache->mag_cache[CPU->id].current = lastmag;
            return lastmag;
        }
    }
    /* current | last are full | nonexistent, allocate new */
    /* We do not want to sleep just because of caching */
    /* Especially we do not want reclaiming to start, as
     * this would deadlock */
    newmag = slab_alloc(&mag_cache, FRAME_ATOMIC | FRAME_NO_RECLAIM);
    if (!newmag)
        return NULL;
    newmag->size = SLAB_MAG_SIZE;
    newmag->busy = 0;
 
    /* Flush last to magazine list */
    if (lastmag)
        put_mag_to_cache(cache, lastmag);
 
    /* Move current as last, save new as current */
    cache->mag_cache[CPU->id].last = cmag; 
    cache->mag_cache[CPU->id].current = newmag;
 
    return newmag;
}
 
/**
 * Put object into CPU-cache magazine
 *
 * @return 0 - success, -1 - could not get memory
 */
static int magazine_obj_put(slab_cache_t *cache, void *obj)
{
    slab_magazine_t *mag;
 
    if (!CPU)
        return -1;
 
    spinlock_lock(&cache->mag_cache[CPU->id].lock);
 
    mag = make_empty_current_mag(cache);
    if (!mag) {
        spinlock_unlock(&cache->mag_cache[CPU->id].lock);
        return -1;
    }
   
    mag->objs[mag->busy++] = obj;
 
    spinlock_unlock(&cache->mag_cache[CPU->id].lock);
    atomic_inc(&cache->cached_objs);
    return 0;
}
 
 
/**************************************/
/* Slab cache functions */
 
/** Return number of objects that fit in certain cache size */
static unsigned 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 unsigned int badness(slab_cache_t *cache)
{
    unsigned int objects;
    unsigned 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 mag_cache structure in slab cache
 */
static void make_magcache(slab_cache_t *cache)
{
    unsigned int i;
   
    ASSERT(_slab_initialized >= 2);
 
    cache->mag_cache = malloc(sizeof(slab_mag_cache_t) * config.cpu_count,
        0);
    for (i = 0; i < config.cpu_count; i++) {
        memsetb(&cache->mag_cache[i], sizeof(cache->mag_cache[i]), 0);
        spinlock_initialize(&cache->mag_cache[i].lock,
            "slab_maglock_cpu");
    }
}
 
/** 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), int (*destructor)(void *obj),
    int flags)
{
    int pages;
    ipl_t ipl;
 
    memsetb(cache, sizeof(*cache), 0);
    cache->name = name;
 
    if (align < sizeof(unative_t))
        align = sizeof(unative_t);
    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->slablock, "slab_lock");
    spinlock_initialize(&cache->maglock, "slab_maglock");
    if (!(cache->flags & SLAB_CACHE_NOMAGAZINE))
        make_magcache(cache);
 
    /* Compute slab sizes, object counts in slabs etc. */
    if (cache->size < SLAB_INSIDE_SIZE)
        cache->flags |= SLAB_CACHE_SLINSIDE;
 
    /* Minimum slab order */
    pages = SIZE2FRAMES(cache->size);
    /* We need the 2^order >= pages */
    if (pages == 1)
        cache->order = 0;
    else
        cache->order = fnzb(pages - 1) + 1;
 
    while (badness(cache) > SLAB_MAX_BADNESS(cache)) {
        cache->order += 1;
    }
    cache->objects = comp_objects(cache);
    /* If info fits in, put it inside */
    if (badness(cache) > sizeof(slab_t))
        cache->flags |= SLAB_CACHE_SLINSIDE;
 
    /* Add cache to cache list */
    ipl = interrupts_disable();
    spinlock_lock(&slab_cache_lock);
 
    list_append(&cache->link, &slab_cache_list);
 
    spinlock_unlock(&slab_cache_lock);
    interrupts_restore(ipl);
}
 
/** Create slab cache  */
slab_cache_t *
slab_cache_create(char *name, size_t size, size_t align,
    int (*constructor)(void *obj, int kmflag), int (*destructor)(void *obj),
    int flags)
{
    slab_cache_t *cache;
 
    cache = slab_alloc(&slab_cache_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
 */
static count_t _slab_reclaim(slab_cache_t *cache, int flags)
{
    unsigned int i;
    slab_magazine_t *mag;
    count_t frames = 0;
    int magcount;
   
    if (cache->flags & SLAB_CACHE_NOMAGAZINE)
        return 0; /* Nothing to do */
 
    /* We count up to original magazine count to avoid
     * endless loop
     */
    magcount = atomic_get(&cache->magazine_counter);
    while (magcount-- && (mag=get_mag_from_cache(cache, 0))) {
        frames += magazine_destroy(cache,mag);
        if (!(flags & SLAB_RECLAIM_ALL) && frames)
            break;
    }
   
    if (flags & SLAB_RECLAIM_ALL) {
        /* Free cpu-bound magazines */
        /* Destroy CPU magazines */
        for (i = 0; i < config.cpu_count; i++) {
            spinlock_lock(&cache->mag_cache[i].lock);
 
            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;
 
            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)
{
    ipl_t ipl;
 
    /* First remove cache from link, so that we don't need
     * to disable interrupts later
     */
 
    ipl = interrupts_disable();
    spinlock_lock(&slab_cache_lock);
 
    list_remove(&cache->link);
 
    spinlock_unlock(&slab_cache_lock);
    interrupts_restore(ipl);
 
    /* 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.");
 
    if (!(cache->flags & SLAB_CACHE_NOMAGAZINE))
        free(cache->mag_cache);
    slab_free(&slab_cache_cache, 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)
        result = slab_obj_create(cache, flags);
 
    interrupts_restore(ipl);
 
    if (result)
        atomic_inc(&cache->allocated_objs);
 
    return result;
}
 
/** Return object to cache, use slab if known  */
static void _slab_free(slab_cache_t *cache, void *obj, slab_t *slab)
{
    ipl_t ipl;
 
    ipl = interrupts_disable();
 
    if ((cache->flags & SLAB_CACHE_NOMAGAZINE) ||
        magazine_obj_put(cache, obj)) {
        slab_obj_destroy(cache, obj, slab);
 
    }
    interrupts_restore(ipl);
    atomic_dec(&cache->allocated_objs);
}
 
/** Return slab object to cache */
void slab_free(slab_cache_t *cache, void *obj)
{
    _slab_free(cache, obj, NULL);
}
 
/* 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);
 
    /* TODO: Add assert, that interrupts are disabled, otherwise
     * memory allocation from interrupts can deadlock.
     */
 
    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)
{
    int skip = 0;
 
    printf("slab name        size     pages  obj/pg slabs  cached allocated"
        " ctl\n");
    printf("---------------- -------- ------ ------ ------ ------ ---------"
        " ---\n");
 
    while (true) {
        slab_cache_t *cache;
        link_t *cur;
        ipl_t ipl;
        int i;
 
        /*
         * We must not hold the slab_cache_lock spinlock when printing
         * the statistics. Otherwise we can easily deadlock if the print
         * needs to allocate memory.
         *
         * Therefore, we walk through the slab cache list, skipping some
         * amount of already processed caches during each iteration and
         * gathering statistics about the first unprocessed cache. For
         * the sake of printing the statistics, we realese the
         * slab_cache_lock and reacquire it afterwards. Then the walk
         * starts again.
         *
         * This limits both the efficiency and also accuracy of the
         * obtained statistics. The efficiency is decreased because the
         * time complexity of the algorithm is quadratic instead of
         * linear. The accuracy is impacted because we drop the lock
         * after processing one cache. If there is someone else
         * manipulating the cache list, we might omit an arbitrary
         * number of caches or process one cache multiple times.
         * However, we don't bleed for this algorithm for it is only
         * statistics.
         */
 
        ipl = interrupts_disable();
        spinlock_lock(&slab_cache_lock);
 
        for (i = 0, cur = slab_cache_list.next;
            i < skip && cur != &slab_cache_list;
            i++, cur = cur->next)
            ;
 
        if (cur == &slab_cache_list) {
            spinlock_unlock(&slab_cache_lock);
            interrupts_restore(ipl);
            break;
        }
 
        skip++;
 
        cache = list_get_instance(cur, slab_cache_t, link);
 
        char *name = cache->name;
        uint8_t order = cache->order;
        size_t size = cache->size;
        unsigned int objects = cache->objects;
        long allocated_slabs = atomic_get(&cache->allocated_slabs);
        long cached_objs = atomic_get(&cache->cached_objs);
        long allocated_objs = atomic_get(&cache->allocated_objs);
        int flags = cache->flags;
       
        spinlock_unlock(&slab_cache_lock);
        interrupts_restore(ipl);
       
        printf("%-16s %8" PRIs " %6d %6u %6ld %6ld %9ld %-3s\n",
            name, size, (1 << order), objects, allocated_slabs,
            cached_objs, allocated_objs,
            flags & SLAB_CACHE_SLINSIDE ? "in" : "out");
    }
}
 
void slab_cache_init(void)
{
    int i, size;
 
    /* Initialize magazine cache */
    _slab_cache_create(&mag_cache, "slab_magazine",
        sizeof(slab_magazine_t) + SLAB_MAG_SIZE * sizeof(void*),
        sizeof(uintptr_t), NULL, NULL, SLAB_CACHE_NOMAGAZINE |
        SLAB_CACHE_SLINSIDE);
    /* Initialize slab_cache cache */
    _slab_cache_create(&slab_cache_cache, "slab_cache",
        sizeof(slab_cache_cache), sizeof(uintptr_t), NULL, NULL,
        SLAB_CACHE_NOMAGAZINE | SLAB_CACHE_SLINSIDE);
    /* Initialize external slab cache */
    slab_extern_cache = slab_cache_create("slab_extern", sizeof(slab_t), 0,
        NULL, NULL, SLAB_CACHE_SLINSIDE | SLAB_CACHE_MAGDEFERRED);
 
    /* Initialize structures for malloc */
    for (i = 0, size = (1 << SLAB_MIN_MALLOC_W);
        i < (SLAB_MAX_MALLOC_W - SLAB_MIN_MALLOC_W + 1);
        i++, size <<= 1) {
        malloc_caches[i] = slab_cache_create(malloc_names[i], size, 0,
            NULL, NULL, SLAB_CACHE_MAGDEFERRED);
    }
#ifdef CONFIG_DEBUG       
    _slab_initialized = 1;
#endif
}
 
/** Enable cpu_cache
 *
 * Kernel calls this function, when it knows the real number of
 * processors.
 * Allocate slab for cpucache and enable it on all existing
 * slabs that are SLAB_CACHE_MAGDEFERRED
 */
void slab_enable_cpucache(void)
{
    link_t *cur;
    slab_cache_t *s;
 
#ifdef CONFIG_DEBUG
    _slab_initialized = 2;
#endif
 
    spinlock_lock(&slab_cache_lock);
   
    for (cur = slab_cache_list.next; cur != &slab_cache_list;
        cur = cur->next){
        s = list_get_instance(cur, slab_cache_t, link);
        if ((s->flags & SLAB_CACHE_MAGDEFERRED) !=
            SLAB_CACHE_MAGDEFERRED)
            continue;
        make_magcache(s);
        s->flags &= ~SLAB_CACHE_MAGDEFERRED;
    }
 
    spinlock_unlock(&slab_cache_lock);
}
 
/**************************************/
/* kalloc/kfree functions             */
void *malloc(unsigned int size, int flags)
{
    ASSERT(_slab_initialized);
    ASSERT(size && size <= (1 << SLAB_MAX_MALLOC_W));
   
    if (size < (1 << SLAB_MIN_MALLOC_W))
        size = (1 << SLAB_MIN_MALLOC_W);
 
    int idx = fnzb(size - 1) - SLAB_MIN_MALLOC_W + 1;
 
    return slab_alloc(malloc_caches[idx], flags);
}
 
void *realloc(void *ptr, unsigned int size, int flags)
{
    ASSERT(_slab_initialized);
    ASSERT(size <= (1 << SLAB_MAX_MALLOC_W));
   
    void *new_ptr;
   
    if (size > 0) {
        if (size < (1 << SLAB_MIN_MALLOC_W))
            size = (1 << SLAB_MIN_MALLOC_W);
        int idx = fnzb(size - 1) - SLAB_MIN_MALLOC_W + 1;
       
        new_ptr = slab_alloc(malloc_caches[idx], flags);
    } else
        new_ptr = NULL;
   
    if ((new_ptr != NULL) && (ptr != NULL)) {
        slab_t *slab = obj2slab(ptr);
        memcpy(new_ptr, ptr, min(size, slab->cache->size));
    }
   
    if (ptr != NULL)
        free(ptr);
   
    return new_ptr;
}
 
void free(void *ptr)
{
    if (!ptr)
        return;
 
    slab_t *slab = obj2slab(ptr);
    _slab_free(slab->cache, ptr, slab);
}
 
/** @}
 */
 
Subversion Repositories HelenOS

(root)/branches/dd/kernel/generic/src/mm/slab.c – Rev 4055 → 4201
