Ublk

[Kampadais]

Which issue(s) this PR fixes: Issues https://github.com/longhorn/longhorn/issues/5159 , https://github.com/longhorn/longhorn/issues/6600

I am reposting this PR because i think it is a solid solution on integrating ublk with longhorn updated with more benchmarks on a more real-life enviroment

What this PR does / why we need it: This PR uses @derekbit 's POC ubdsrv to integrate ublk with longhorn-engine and adds support for multiple frontend queues.

Using ublk as a frontend option significantly boosts the IOPS in the frontend part of the engine. In our tests, we measure up to ~280k IOPS at the frontend (before the controller communicates with the replicas). Those IOPS are bounded because of my setup.

For the benchmarks i used the folowing setup : CPU : Intel(R) Xeon(R) CPU E5-2620 v2 @ 2.10GHz RAM: 128GB Disk: Samsung 860 Evo SSD 250GB Network : 10Gbps

One replica , one controller , 2 machines in a local cluster On the ublk :       Ublk frontend queues : 6       Controller-Replica connections : 6

The fio command used for testing IOPS: sudo fio --name=read_iops --filename=/dev/ublkb0 --size=5G --numjobs=12 --time_based --runtime=30s --ramp_time=2s --ioengine=libaio --direct=1 --verify=0 --bs=4K --iodepth=64 --rw=randwrite --group_reporting=1 fio command used for testing Bandwidth:

sudo fio --name=bandwidth --filename=/dev/ublkb0 --size=5G --numjobs=12--time_based --runtime=30s --ramp_time=2s --ioengine=libaio --direct=1 --verify=0 --bs=1M --iodepth=64 --rw=read --group_reporting=1

*Replica R/W disabled means that the replica code is altered in order to answer dummy replies and not do the actual R/W in the Linux sparse files.

Note that the frontend performance was bounded by my pc's process power. Using a more powerful pc , ublk can achieve close to raw disk speeds. Based on these findings we can see that there is also need to improve other parts of the system too in order to utilize ublk fully.

Special notes for your reviewer: In order to replicate the results you will need my version of ubdsrv installed: https://github.com/Kampadais/ubdsrv

To run the controller with ublk frontend, 6 frontend queues and 6 replica-streams: ./longhorn controller test --frontend ublk --size 1g --current-size 1g --frontend-queues 6 --replica-streams 6 --replica tcp://....:9502

We are still the need of a go-ublk-helper because the whole startup procedure is within the frontend.go file and monitoring status is limited. There is also a limitation regarding the name of the block device provided by ublk.

Additional documentation or context

Summary by CodeRabbit

• New Features

  • Introduced a new command-line flag frontend-queues for specifying the number of frontend queues.
  • Added a new ublk frontend package for managing ublk devices, including methods for initialization, starting, and shutting down the device.

• Bug Fixes

  • Enhanced error handling for the new command-line flag integration.

• Documentation

  • Updated comments to reflect the addition of new parameters and functionalities.

• Chores

  • Modified the Dockerfile to include new dependencies and build steps for the ubdsrv component.

[mergify[bot]]

This pull request is now in conflict. Could you fix it @Kampadais? 🙏

[github-actions[bot]]

This PR is stale because it has been open for 45 days with no activity. Remove stale label or comment or this will be closed in 10 days.

[coderabbitai[bot]]

Walkthrough

The changes introduce a new command-line flag frontend-queues in the ControllerCmd function, allowing users to specify the number of frontend queues. This flag is integrated into the controller's initialization process and affects the instantiation of the ublk frontend. Additionally, the Dockerfile is updated to include dependencies for a new component, ubdsrv, along with its build steps. A new package ublk is created to manage ublk devices, encapsulating various functionalities related to their operation.

Changes

File	Change Summary
app/cmd/controller.go	Added frontend-queues command-line flag; updated method signatures for NewFrontend and NewController to include frontendQueues.
package/Dockerfile	Added installation commands for development tools; introduced UBD_COMMIT_ID environment variable; added build steps for liburing and ubdsrv.
pkg/controller/control.go	Added frontendQueues field to Controller struct; updated NewController method signature to include frontendQueues.
pkg/controller/init_frontend.go	Updated NewFrontend method signature to include frontendQueues; added case for ublk frontend type.
pkg/frontend/ublk/frontend.go	Introduced ublk package with methods for managing ublk devices; added multiple methods and a struct DataProcessorWrapper for handling data operations.

Assessment against linked issues

Objective	Addressed	Explanation
Implementation of the single queue longhorn-ublk (#5159)	✅
Implementation of go-ublk-helper (#5159)	✅
Integrate go-ublk-helper and longhorn-engine (#5159)	✅
Error handling (#5159)	❌	Specific error handling not detailed.
Performance benchmark (#5159)	❓	Changes do not specify benchmarks.

Poem

🐇 In the meadow where changes bloom,
A flag for queues dispels the gloom.
With ublk's might, we pave the way,
For faster paths in bright array.
So hop along, let’s cheer and play,
For Longhorn's future shines today! 🌼

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[PhanLe1010]

Adding the PR in backlog milestone so that it won't stale