Improve memory defragmentation (#7788)

[sre-bot]

cherry-pick #7788 to release-3.0

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Signed-off-by: Breezewish breezewish@pingcap.com

What problem does this PR solve?

Problem Summary:

There was a PR fixing the memory fragmentation issue. However there is a bug in the PR that the defragmentation will not be very effective after running for a long time. This PR fixes it.

What is changed and how it works?

What's Changed: Bug fix.

Related changes

• Need to cherry-pick to the release branch

Check List

• Manual test: Tested a cluster that has been started for > 1 day, confirmed that sys_getdents are now called by 10 minutes interval, instead of 15 secods.

[pid 64038] 15:24:16.579973 getdents(556</data3/wenxuan_kv1_exp/data/snap>, /* 2 entries */, 32768) = 48 <0.000037>
[pid 64038] 15:24:16.580232 getdents(556</data3/wenxuan_kv1_exp/data/snap>, /* 0 entries */, 32768) = 0 <0.000027>
[pid 64039] 15:25:16.582008 getdents(555</data3/wenxuan_kv1_exp/data/snap>, /* 2 entries */, 32768) = 48 <0.000026>
[pid 64039] 15:25:16.582121 getdents(555</data3/wenxuan_kv1_exp/data/snap>, /* 0 entries */, 32768) = 0 <0.000013>
[pid 64039] 15:26:16.584170 getdents(555</data3/wenxuan_kv1_exp/data/snap>, /* 2 entries */, 32768) = 48 <0.000048>
[pid 64039] 15:26:16.584302 getdents(555</data3/wenxuan_kv1_exp/data/snap>, /* 0 entries */, 32768) = 0 <0.000023>
[pid 64039] 15:27:16.586493 getdents(3</data3/wenxuan_kv1_exp/data/snap>, /* 2 entries */, 32768) = 48 <0.000038>
[pid 64039] 15:27:16.586632 getdents(3</data3/wenxuan_kv1_exp/data/snap>, /* 0 entries */, 32768) = 0 <0.000022>
[pid 64078] 15:27:16.671043 getdents(3</proc/63302/task>, /* 187 entries */, 32768) = 5968 <0.000183>
[pid 64078] 15:27:16.671527 getdents(3</proc/63302/task>, /* 0 entries */, 32768) = 0 <0.000016>
[pid 64039] 15:28:16.588570 getdents(539</data3/wenxuan_kv1_exp/data/snap>, /* 2 entries */, 32768) = 48 <0.000046>
[pid 64039] 15:28:16.588703 getdents(539</data3/wenxuan_kv1_exp/data/snap>, /* 0 entries */, 32768) = 0 <0.000021>
[pid 64039] 15:29:16.590764 getdents(556</data3/wenxuan_kv1_exp/data/snap>, /* 2 entries */, 32768) = 48 <0.000028>
[pid 64039] 15:29:16.590885 getdents(556</data3/wenxuan_kv1_exp/data/snap>, /* 0 entries */, 32768) = 0 <0.000041>
[pid 64038] 15:30:16.593033 getdents(513</data3/wenxuan_kv1_exp/data/snap>, /* 2 entries */, 32768) = 48 <0.000030>
[pid 64038] 15:30:16.593173 getdents(513</data3/wenxuan_kv1_exp/data/snap>, /* 0 entries */, 32768) = 0 <0.000027>
[pid 64038] 15:31:16.595139 getdents(555</data3/wenxuan_kv1_exp/data/snap>, /* 2 entries */, 32768) = 48 <0.000064>
[pid 64038] 15:31:16.595302 getdents(555</data3/wenxuan_kv1_exp/data/snap>, /* 0 entries */, 32768) = 0 <0.000016>
[pid 64039] 15:32:16.597362 getdents(556</data3/wenxuan_kv1_exp/data/snap>, /* 2 entries */, 32768) = 48 <0.000039>
[pid 64039] 15:32:16.597480 getdents(556</data3/wenxuan_kv1_exp/data/snap>, /* 0 entries */, 32768) = 0 <0.000022>

Release note

Improve memory defragmentation.

[sre-bot]

/run-all-tests

[breezewish]

/run-all-tests