cherry-pick #3592 to release-5.0
You can switch your code base to this Pull Request by using git-extras:

# In pd repo:
git pr https://github.com/tikv/pd/pull/3605

After apply modifications, you can push your change to this PR via:

git push git@github.com:ti-srebot/pd.git pr/3605:release-5.0-9d9c8eedca3a

What problem does this PR solve?

issue: #3589

What is changed and how it works?

core regionScoreV2 calculator, store's score will increase rapidly when it disk space less than F

Check List

Tests

• Integration test
• Manual test (add detailed scripts or steps below)

Code changes
when I use math to consider score similator in low space：

the score will be mostly affect by C, so their socres is different,the lower disk has few score than higher disk. so it will move region to lower store to run out of disk :
similator ：

What is changed and how it works?

core regionScoreV2 calculator, store's score will increase rapidly when it disk space less than F.
the F param is not 20G, it should be set by the store's disk space , F will be set:

F=max(50,capacity*(1-lowSpaceRatio))

I want to the score should be similar when they has same free space in low disk space, so use linear calculator.

similator result：

test result：

it work well in low space

Side effects

Related changes

• Need to cherry-pick to the release branch

Release note

• modify score calculator to satisfy isomerous stores