Set max_threads according to the number of physical cpu cores

[xzhangxian1008]

What problem does this PR solve?

Issue Number: close #6480

Problem Summary:

What is changed and how it works?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

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• bestwoody
• yibin87

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[xzhangxian1008]

/cc @windtalker @yibin87

[JaySon-Huang]

Can we remove the contrib/libcpuid ?

[xzhangxian1008]

Can we remove the contrib/libcpuid ?

After decoupling the storage and compute, compute layer will have to get these information by itself, instead of from proxy.

[yibin87]

Please double check the "server_info.cpu_info.physical_cores" value in docker env. Others lgtm

[Lloyd-Pottiger]

why is physical cpu cores? IMO, logical_cpu_cores / 2 is better

[Lloyd-Pottiger]

why is physical cpu cores? IMO, logical_cpu_cores / 2 is better

the number of physical cpu cores in CH is also equal to logical_cpu_cores / 2, rather than the number of real hardware cores.

[xzhangxian1008]

/run-all-tests

[windtalker]

LGTM

[xzhangxian1008]

/run-all-tests

[windtalker]

/merge

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[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 5f7408d

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #6489.

[breezewish]

https://github.com/ClickHouse/ClickHouse/blob/master/src/Common/getNumberOfPhysicalCPUCores.cpp#L51

In clickhouse, when cores < 32, it will set max threads according to logical cores instead of physical cores. May be we could follow this pattern?

[JaySon-Huang]

The reason of changes in this PR is:

https://github.com/pingcap/tiflash/pull/6430/files#diff-64dad304ef83932f1dc505de02b2bca69271c6af8023291c2a71c61778e84dc2R168-R172
In #6430, SettingsMaxThreads is set to logical CPU cores but not physical cores. After that, TiFlash uses more threads to run some queries, which may bring performance regression. So keep the old logic by this PR.