/*
* 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)
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(&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;
} 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 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(&cache->magazines, &mag->link);
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);
}
/** 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);
}
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);
}
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\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\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 */
}