Do you know that there are two limits about dirty (modified but not flushed to disk) blocks of InnoDB buffer pool? One is the limit of “amount”. The other is the limit of “age”. — limit of “amount” — As you know, buffer pool of InnoDB works as write-back cache of its datafiles. If the buffer pool is filled by dirty blocks, InnoDB cannot allocate new blocks without flushing the dirty blocks and the
![Adaptive checkpointing](https://cdn-ak-scissors.b.st-hatena.com/image/square/813dd3dc568d314fcc47030e0bde7dec886aa88a/height=288;version=1;width=512/https%3A%2F%2Fwww.percona.com%2Fblog%2Fwp-content%2Fuploads%2F2008%2F11%2Fadaptive_flush_1.png)