On Tue, Jan 3, 2012 at 3:34 PM, Orit Wasserman <owass...@redhat.com> wrote:
> +static unsigned long cache_get_cache_pos(ram_addr_t address)
> +{
> + unsigned long pos;
> +
> + assert(cache_num_buckets);
> + pos = (address/TARGET_PAGE_SIZE) & (cache_num_buckets - 1);
Where do we guarantee that cache_num_buckets is a power of 2?
> +static void cache_insert(unsigned long addr, uint8_t *pdata)
> +{
> + unsigned long pos;
> + int slot = -1;
> + CacheBucket *bucket;
> +
> + pos = cache_get_cache_pos(addr);
> + assert(page_cache);
> + bucket = &page_cache[pos];
> + slot = cache_get_oldest(bucket); /* evict LRU */
> +
> + /* actual update of entry */
> + CacheItem *it = cache_item_get(pos, slot);
> + if (!it->it_data) {
> + cache_num_items++;
> + }
> + g_free(it->it_data);
> +
> + it->it_data = g_malloc0(TARGET_PAGE_SIZE);
> + memcpy(it->it_data, pdata, TARGET_PAGE_SIZE);
If we're evicting an entry:
1. Free existing data.
2. Allocate new data.
3. Zero new data.
4. Memcpy pdata into new data.
That does a bunch of extra work. How about:
1. Memcpy pdata over old data.
So:
if (!it->it_data) {
cache_num_items++;
it->it_data = g_malloc(TARGET_PAGE_SIZE);
}
memcpy(it->it_data, pdata, TARGET_PAGE_SIZE);
