Orit Wasserman <owass...@redhat.com> wrote:
> Add LRU page cache mechanism.
> The page are accessed by their address.
>
> +
> +typedef struct CacheItem {
> + ram_addr_t it_addr;
> + unsigned long it_age;
> + uint8_t *it_data;
> +} CacheItem;
> +
> +typedef struct CacheBucket {
> + CacheItem bkt_item[CACHE_N_WAY];
> +} CacheBucket;
> +
> +static CacheBucket *page_cache;
> +static int64_t cache_num_buckets;
> +static uint64_t cache_max_item_age;
> +static int64_t cache_num_items;
I will put this 3 variables inside CacheBucket, just to make clear that
they are related.
> +
> +static void cache_init(int64_t num_buckets);
> +static void cache_fini(void);
> +static int cache_is_cached(ram_addr_t addr);
> +static int cache_get_oldest(CacheBucket *buck);
> +static int cache_get_newest(CacheBucket *buck, ram_addr_t addr);
> +static void cache_insert(ram_addr_t id, uint8_t *pdata, int use_buffer);
> +static unsigned long cache_get_cache_pos(ram_addr_t address);
> +static CacheItem *cache_item_get(unsigned long pos, int item);
> +static void cache_resize(int64_t new_size);
None of this are needed. Notice that cache_resize is not marked static later.
> +
> +/***********************************************************/
We normally don't use this to split code O:-)
> +static void cache_init(int64_t num_bytes)
> +{
> + int i;
> +
> + cache_num_items = 0;
> + cache_max_item_age = 0;
> + cache_num_buckets = num_bytes / (TARGET_PAGE_SIZE * CACHE_N_WAY);
Do we check that num_bytes is not negative? I can't see.
> + assert(cache_num_buckets);
> + DPRINTF("Setting cache buckets to %lu\n", cache_num_buckets);
> +
> + assert(!page_cache);
Only user of this function make page_cache = NULL before calling.
Returning an error looks more sensible, but haven't yet looked at the
next patechs to see if we have a way to do anything good with the error.
> + page_cache = (CacheBucket *)g_malloc((cache_num_buckets) *
> + sizeof(CacheBucket));
g_malloc() returns void * (well gpointer, but that is void*). We don't
need to cast its return.
> +static int cache_is_cached(ram_addr_t addr)
> +{
> + unsigned long pos = cache_get_cache_pos(addr);
> +
> + assert(page_cache);
> + CacheBucket *bucket = &page_cache[pos];
> + return cache_get_newest(bucket, addr);
> +}
Can we make this function return a bool? Basically we put that anything
!= -1 means cached, -1 means non-cached.
> +
> +static void cache_insert(unsigned long addr, uint8_t *pdata, int
> use_buffer)
Change use_buffer to a bool?
or even better, just remove the parameter altogether and change inteface
to:
cache_insert(addr, foo, 1) -> cache_insert(addr, foo)
cache_insert(addr, foo, 0) -> cache_insert(addr, g_memdup(foo,TARGET_PAGE_SIZE))
and remove all the use_buffer() code?
> +{
> + unsigned long pos;
> + int slot = -1;
> + CacheBucket *bucket;
> +
> + pos = cache_get_cache_pos(addr);
> + assert(page_cache);
Function call in previous line already use page_cache, switch lines or just
remove
the assert?
> +void cache_resize(int64_t new_size)
> +{
> + int64_t new_num_buckets = new_size/(TARGET_PAGE_SIZE * CACHE_N_WAY);
> + CacheBucket *old_page_cache = page_cache;
> + int i;
> + int64_t old_num_buckets = cache_num_buckets;
> +
> + /* same size */
> + if (new_num_buckets == cache_num_buckets) {
> + return;
> + }
Shouldn't we check that new_num_buckets makes sense?
> + /* cache was not inited */
> + if (page_cache == NULL) {
> + return;
> + }
> +
> + /* create a new cache */
> + page_cache = NULL;
> + cache_init(new_size);
Later, Juan.
