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The buffer pool is an area in main memory where InnoDB caches table and index data as it is accessed. The buffer pool permits frequently used data to be accessed directly from memory, which speeds up processing. On dedicated servers, up to 80% of physical memory is often assigned to the buffer pool.
缓冲池是内存中的一块次要区域用来缓存 InnoDB 的表和索引数据。缓冲池能够将常常应用的数据保留在内存用于间接拜访。在专用数据库服务器中，高达 80% 的物理内存能够用来作为缓冲池。
Buffer Pool LRU Algorithm
The buffer pool is managed as a list using a variation of the LRU algorithm. When room is needed to add a new page to the buffer pool, the least recently used page is evicted and a new page is added to the middle of the list. This midpoint insertion strategy treats the list as two sublists:
At the head, a sublist of new (“young”)pages that were accessed recently
At the tail, a sublist of old pages that were accessed less recently
缓冲池是用 LRU 算法来进行治理的。当缓冲池中要插入一个新页时，缓冲池中最近起码应用的页将会被驱赶，新页将会被增加到两头列表中。两头插入策略将列表分成两个子列表：
在头部，是比拟新的列表，会被常常应用。
在尾部，是比拟旧的列表，被应用的比拟少。
The algorithm keeps frequently used pages in the new sublist. The old sublist contains less frequently used pages; these pages are candidates for eviction.
LRU 算法会将常常拜访的页放弃在新子列表中。老的子列表中蕴含拜访比拟少的页，这些页会作为被驱赶的页候选。
Buffer Pool Configuration
You can configure the various aspects of the buffer pool to improve performance.
能够从很多方面配置缓冲池来进步性能。
Ideally, you set the size of the buffer pool to as large a value as practical, leaving enough memory for other processes on the server to run without excessive paging. The larger the buffer pool, the more InnoDB acts like an in-memory database, reading data from disk once and then accessing the data from memory during subsequent reads. See
能够通过进步缓冲池的大小来进步数据库性能。缓冲池越大能包容的数据页越多，InnoDB 就越像一个页游内存数据库。
On 64-bit systems with sufficient memory, you can split the buffer pool into multiple parts to minimize contention for memory structures among concurrent operations. For details
在 64 位操作系统，在内存短缺的状况下能够将缓冲池分为多个局部。
You can keep frequently accessed data in memory regardless of sudden spikes of awww.sangpi.comctivity from operations that would bring large amounts of infrequently accessed data into the buffer pool. For details,
能够将常常拜访的数据在缓冲池中做长久化。
You can control how and when to perform read-ahead requests to prefetch pages into the buffer pool asynchronously in anticipation that the pages are needed soon. For details, see 缓冲池能够做预读。
You can control when background flushing occurs and whether or not the rate of flushing is dynamically adjusted based on workload. For details, see
能够管制缓冲池的刷新频率机刷新比例。
You can configure how InnoDB preserves the current buffer pool state to avoid a lengthy warmup period after a server restart. For details, see
能够保留缓冲池的状态，防止长时间重启。
Monitoring the Buffer Pool Using the InnoDB Standard Monitor
InnoDB Standard Monitor output, which can be accessed using provides metrics regarding operation of the buffer pool. Buffer pool metrics are located in the BUFFER POOL AND MEMORY section of InnoDB Standard Monitor output:
能够通过 show engine innodb status; 命令去监控缓冲池的状态。缓冲池的指标能够重 BUFFER POOL AND MEMORY 局部查看：