Backfill optimization

src/engine/engine_bf.c

@@ -68,11 +68,21 @@ static void _ocf_backfill_complete(struct ocf_request *req, int error)
 	}
 }
 
+#define __entries_not_adjacent(__req, __i, __j) \
+	__req->map[__i].coll_idx + 1 != __req->map[__j].coll_idx
+
+#define __is_the_last_chunk(__req, __i) (__i == (__req->core_line_count - 1))
+
+#define __skip_on_the_last_entry(__skip, __req, __i) \
+	__skip * (int)__is_the_last_chunk(__req, __i)
+
 static int _ocf_backfill_do(struct ocf_request *req)
 {
 	ocf_cache_t cache = req->cache;
-	uint64_t addr, bytes, total_bytes = 0, addr_next = 0;
-	uint64_t seek, skip;
+	uint64_t metadata_offset = cache->device->metadata_offset;
+	ocf_cache_line_size_t cache_line_size = ocf_line_size(cache);
+	uint64_t addr, bytes, total_bytes = 0;
+	uint64_t seek, skip, last_chunk_size;
 	uint32_t i;
 
 	req->data = req->cp_data;
@@ -84,9 +94,9 @@ static int _ocf_backfill_do(struct ocf_request *req)
 	req->cache_forward_end = _ocf_backfill_complete;
 
 	if (ocf_engine_is_sequential(req)) {
-		addr = cache->device->metadata_offset;
-		addr += req->map[0].coll_idx * ocf_line_size(cache);
-		addr += req->addr % ocf_line_size(cache);
+		addr = metadata_offset;
+		addr += req->map[0].coll_idx * cache_line_size;
+		addr += req->addr % cache_line_size;
 
 		ocf_core_stats_cache_block_update(req->core, req->part_id,
 				OCF_WRITE, req->bytes);
@@ -96,49 +106,40 @@ static int _ocf_backfill_do(struct ocf_request *req)
 		return 0;
 	}
 
+	seek = req->addr % cache_line_size;
+	last_chunk_size = (req->addr + req->bytes) % cache_line_size;
+	skip = (cache_line_size - last_chunk_size) % cache_line_size;
+
 	ocf_req_forward_cache_get(req);
 	for (i = 0; i < req->core_line_count; i++) {
-		if (addr_next) {
-			addr = addr_next;
-		} else {
-			addr  = req->map[i].coll_idx;
-			addr *= ocf_line_size(cache);
-			addr += cache->device->metadata_offset;
-		}
-		bytes = ocf_line_size(cache);
-
-		if (i == 0) {
-			seek = req->addr % ocf_line_size(cache);
-			addr += seek;
-			bytes -= seek;
-		}
-
 		if (req->map[i].status == LOOKUP_HIT) {
-			/* This is the 1st cache line in the interval,
-			 * and it's a hit. Don't write it to the cache.
-			 */
-			addr_next = 0;
-			total_bytes += bytes;
+			/* This is the 1st cache line in the interval, and it's
+			   a hit. Don't write it to the cache */
+			total_bytes += cache_line_size;
+			total_bytes -= seek;
+			/* Seek should be taken into account for the first chunk
+			   only */
+			seek = 0;
 			continue;
 		}
 
-		for (; i < (req->core_line_count - 1); i++) {
-			addr_next = req->map[i + 1].coll_idx;
-			addr_next *= ocf_line_size(cache);
-			addr_next += cache->device->metadata_offset;
+		addr = metadata_offset;
+		addr += req->map[i].coll_idx * cache_line_size;
 
-			if (addr_next != (addr + bytes))
+		bytes = cache_line_size;
+		for (; i < (req->core_line_count - 1); i++) {
+			if (__entries_not_adjacent(req, i, i + 1))
 				break;
 
-			bytes += ocf_line_size(cache);
+			bytes += cache_line_size;
 		}
 
-		if (i == (req->core_line_count - 1)) {
-			skip = (ocf_line_size(cache) -
-					((req->addr + req->bytes) %
-					 ocf_line_size(cache))) % ocf_line_size(cache);
-			bytes -= skip;
-		}
+		/* Seek should be taken into account for the first chunk only */
+		addr += seek;
+		bytes -= seek;
+		seek = 0;
+
+		bytes -= __skip_on_the_last_entry(skip, req, i);
 
 		bytes = OCF_MIN(bytes, req->bytes - total_bytes);