Tag History module has interrupted data storage

My project ran well for servral months. Nowdays Tag History module has interrupted data storage. I found that CPU utilization of database server reaches 40%. Now I restart the database server. It dropped below 10%。Besides, Partition Units changed from 1 month to 1 week. Max Active connections in the database has been expanded.
And database server property follows:Processor Interl(R) Xeon(R) silver 4114 CPU @ 2.2GHz 2.19GHz /4 core /16GB RAM.

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The total Tag Provider number is nearly 200,000. Different Historical Provider uses different store metricx. Someone store metricxs average time is 38.6 per second. Aggregate Throughput is bettween 17.8 and about 100 per second.
At present, the problem of database has been temporarily solved. I would like to know whether there is a better solution for my case or not. Do I need to buy another tag history module for store data?
Looking forward your reply!

What is your inndb buffer pool size?

Memory buffer size is 250,000.

Run this:
show variables like 'innodb_buffer_pool_size';


the innodb_buffer_pool_size of mysql is 8388608.

You need to increase that. That is the default value.

May I ask that which size is suitable for my case?

I’ve optimized and expanded the innodb_buffer_pool_size to 128MB. Then how to see it works well?