WebSVN – HelenOS-historic – Diff – /kernel/trunk/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.
  */
 #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;
+    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, although
+     * the optimizer might optimize the division out :-/ */
+    for (i=0; i< (1<<cache->order); i++) {
+        ADDR2FRAME(zone, (__address)(data+i*PAGE_SIZE))->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;
+    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);
+    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 low level functions */
+/* 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)
+static count_t slab_obj_destroy(slab_cache_t *cache, void *obj,
+                slab_t *slab)
+{
+    count_t frames = 0;
-    return 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(&cache->partial_slabs, &slab->link);
+    }
+    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;
+            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(&cache->full_slabs, &slab->link);
+    else
+        list_prepend(&cache->partial_slabs, &slab->link);
+    return obj;
+}
 /**************************************/
 /* CPU-Cache slab functions */
 /**
  * Free all objects in magazine and free memory associated with magazine
+ *
- * Assume cpu->lock is locked
+ * 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]);
+        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 frome
+        /* 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, SLAB_ATOMIC | SLAB_NO_RECLAIM);
+        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(&cache->magazines, &mag->link);
-            mag = slab_alloc(&mag_cache, SLAB_ATOMIC | SLAB_NO_RECLAIM);
+            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;
+}
 /**************************************/
-/* Top level SLAB functions */
+/* 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;
-    cache->align = align;
+    if (align)
-    cache->size = ALIGN_UP(size, 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 */
+    /* Destroy full magazines */
-        cur=cache->magazines.next;
+    cur=cache->magazines.prev;
-        while (cur!=&cache->magazines) {
+    while (cur!=&cache->magazines) {
-            mag = list_get_instance(cur, slab_magazine_t, link);
+        mag = list_get_instance(cur, slab_magazine_t, link);
-            cur = cur->next;
+        cur = cur->prev;
-            list_remove(cur->prev);
+        list_remove(cur->next);
-            frames += magazine_destroy(cache,mag);
+        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)
+    if (!result) {
+        spinlock_lock(&cache->lock);
         result = slab_obj_create(cache, flags);
+        spinlock_unlock(&cache->lock);
+    }
     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)
+    if ((cache->flags & SLAB_CACHE_NOMAGAZINE) \
-        slab_obj_destroy(cache, obj);
+        || magazine_obj_put(cache, obj)) {
-    else {
-        if (magazine_obj_put(cache, obj)) /* If magazine put failed */
+        spinlock_lock(&cache->lock);
-            slab_obj_destroy(cache, obj);
+        slab_obj_destroy(cache, obj, NULL);
+        spinlock_unlock(&cache->lock);
+    }
     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\tObj size\n");
+    printf("SLAB name\tOsize\tOrder\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\n", cache->name, cache->size);
+        printf("%s\t%d\t%d\n", cache->name, cache->size, cache->order);
+    }
     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 */
+}

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/generic/src/mm/slab.c – Rev 759 → 762