Fix speed compute

[joccau]

What problem does this PR solve?

fix issue: the average speed isn't accurate(#1405)

What is changed and how it works?

change the Calculation method for speed

Check List

Tests

• Manual test (add detailed scripts or steps below)

command
./br backup full --pd "172.16.6.117:2379" --compression-level 3 --storage "local:///home/zak/new_br"
./br restore full --pd "172.16.6.117:2379" --storage "local:///home/zak/new_br"
log
[2021/08/04 10:03:34.913 +08:00] [INFO] [collector.go:67] ["Full backup success summary"] [total-ranges=45] [ranges-succeed=45] [ranges-failed=0] [backup-checksum=3.515718214s] [backup-fast-checksum=7.003603ms] [backup-total-ranges=58] [backup-total-regions=77] [total-take=14.017946255s] [total-kv=15463846] [total-kv-size=1.859GB] [average-speed=132.6MB/s] ["backup data size(after compressed)"=496.8MB] [BackupTS=426781599562989570]

[2021/08/04 10:06:45.055 +08:00] [INFO] [collector.go:67] ["Full restore success summary"] [total-ranges=37] [ranges-succeed=37] [ranges-failed=0] [split-region=362.373805ms] [restore-checksum=6.890396086s] [restore-ranges=29] [total-take=17.328491842s] ["restore data size(after compressed)"=496.7MB] [total-kv=15462460] [total-kv-size=1.858GB] [average-speed=107.2MB/s]

Release note

• fix the bug that the average speed isn't accurate in backup and restore

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• YuJuncen
• lichunzhu

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[sre-bot]

No release note, Please follow https://github.com/pingcap/community/blob/master/contributors/release-note-checker.md

[lichunzhu]

LGTM

[sre-bot]

No release note, Please follow https://github.com/pingcap/community/blob/master/contributors/release-note-checker.md

[joccau]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• lichunzhu

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

The full list of commands accepted by this bot can be found here.

Reviewer can indicate their review by submitting an approval review.
Reviewer can cancel approval by submitting a request changes review.

[sre-bot]

No release note, Please follow https://github.com/pingcap/community/blob/master/contributors/release-note-checker.md

[3pointer]

/rebuild

[YuJuncen]

/run-integration-test

[YuJuncen]

/merge

[ti-chi-bot]

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

Commit hash: 3c67593

[ti-chi-bot]

In response to a cherrypick label: failed to Push cherry-picked changes in GitHub: pushing failed, output: "remote: hooks/pre-receive: 26: .: Can't open /data/gitrpcd/.app-config/.sh \nTo https://github.com/ti-chi-bot/br\n ! [remote rejected] cherry-pick-1408-to-release-4.0 -> cherry-pick-1408-to-release-4.0 (pre-receive hook declined)\nerror: failed to push some refs to 'https://github.com/ti-chi-bot/br'\n", error: exit status 1

[ti-chi-bot]

In response to a cherrypick label: failed to Push cherry-picked changes in GitHub: pushing failed, output: "remote: hooks/pre-receive: 26: .: Can't open /data/gitrpcd/.app-config/.sh \nTo https://github.com/ti-chi-bot/br\n ! [remote rejected] cherry-pick-1408-to-release-5.1 -> cherry-pick-1408-to-release-5.1 (pre-receive hook declined)\nerror: failed to push some refs to 'https://github.com/ti-chi-bot/br'\n", error: exit status 1

[ti-chi-bot]

In response to a cherrypick label: failed to Push cherry-picked changes in GitHub: pushing failed, output: "remote: hooks/pre-receive: 26: .: Can't open /data/gitrpcd/.app-config/.sh \nTo https://github.com/ti-chi-bot/br\n ! [remote rejected] cherry-pick-1408-to-release-5.0 -> cherry-pick-1408-to-release-5.0 (pre-receive hook declined)\nerror: failed to push some refs to 'https://github.com/ti-chi-bot/br'\n", error: exit status 1

[Mini256]

/cherry-pick release-4.0

[ti-chi-bot]

@Mini256: new pull request created: #1410.

In response to this:

/cherry-pick release-4.0

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[Mini256]

/cherry-pick release-5.0

[Mini256]

/cherry-pick release-5.1

[ti-chi-bot]

@Mini256: new pull request created: #1411.

In response to this:

/cherry-pick release-5.0

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[ti-chi-bot]

@Mini256: new pull request created: #1412.

In response to this:

/cherry-pick release-5.1

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.