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innodb_buffer_pool_instances suggestion #811

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PRR24 opened this issue Dec 15, 2024 · 1 comment
Open

innodb_buffer_pool_instances suggestion #811

PRR24 opened this issue Dec 15, 2024 · 1 comment

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@PRR24
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PRR24 commented Dec 15, 2024

I understand, the property is about to get extinct soon, but for older platforms -- currently mysqltuner suggests always to use innodb_buffer_pool_instances = innodb_buffer_pool_size / 1G (+ checking for hard limits)
Up to my best understanding, it is not recommended to set innodb_buffer_pool_instances (much) higher than CPU core count. If I am correct, would it make sense to integrate it into recommendation?
Or please correct me, if my understanding is incorrect.

@ErickLGonzalez
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innodb_buffer_pool_instances is calculated as 1/2 of (innodb_buffer_pool_size / innodb_buffer_pool_chunk_size)

Pool instances is calculated as 1/4 of available logical processors (Thread(s) per core. Each core can usually handle two threads. In Linux type lscpu and multiply the number of CPUs x Thread(s) per core. In my example, my machine has 8 CPUs and each can handle two threads, my buffer pool instances is 16.

Buffer pool size must always be equal to or a multiple of innodb_buffer_pool_chunk_size * innodb_buffer_pool_instances. If you alter innodb_buffer_pool_chunk_size, innodb_buffer_pool_size is automatically adjusted to a value that is equal to or a multiple of innodb_buffer_pool_chunk_size * innodb_buffer_pool_instances. The adjustment occurs when the buffer pool is initialized.

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