bcache

Q:

1. 大block_size writethrough?
2. fio IOPS with writeback going -> 40k ~ 50k, initialized cache 50k, used cache 40k
3. after trigger_gc, cache_available don't get larger. --> pin: 0, mark: 1(dirty)

code flow:

• writeback:
  
  • request_write -> bch_writeback_add -> bch_writeback_queue -> refill_dirty -> read_dirty -> read_dirty_submit -> write_dirty -> write_dirty_finish
• write_dirty_finish:
  
  • bch_btree_insert
    
    • bch_btree_insert_recurse
      
      • __bkey_put(b->c, insert); // set pin to 0