202f16e799
This series introduces workload prioritization: an extension of the service levels feature which allows specifying "shares" per service level. The number of shares determines the priority of the user which has this service level attached (if multiple are attached then the one with the lowest shares wins). Different service levels will be isolated in the following way: - Each service level gets its own scheduling group with the number of shares (corresponding to the service level's number of shares), which controls the priority of the CPU and I/O used for user operations running on that service level. - Each service level gets two reader concurrency semaphores, one for user reads and the other for read-before-write done for view updates. - Each service level gets its own TCP connections for RPC to prevent priority inversion issues. Because of the mandatory use of scheduling groups, which are a globally limited resource, the number of service levels is now limited to 7 user created service levels + 1 created by default that cannot be removed. This feature has been previously only available in ScyllaDB Enterprise but has been made available for the source available ScyllaDB. The series was created by comparing the master branch with source-available-workbranch / enterprise branch and taking the workload prioritization related parts from the diff, then molding the resulting diff into a proper series. Some very minor changes were made such as fixing whitespace, removing unused or unnecessary code, adding some boilerplate (in api/) which was missing, but otherwise no major changes have been made. No backport is required. Closes scylladb/scylladb#22031 * github.com:scylladb/scylladb: tracing: record scheduling group in trace event record qos: un-shared-from-this standard_service_level_distributed_data_accessor alternator: execute under scheduling group for service level test.py: support multiple commands in prepare_cql in suite.yml docs: add documentation for workload prioritization docs/dev: describe workload prioritization features in service_levels test/auth_cluster: test workload prioritization in service level tests cqlpy/test_service_levels: add workload prioritization tests api: introduce service levels specific API api/cql_server_test: add information about scheduling group db/virtual_tables: add scheduling group column to system.clients test/boost: update service_level_controller_test for workload prio qos: include number of shares in DESCRIBE cql3/statements: update SL statements for workload prioritization transport/server: use scheduling group assigned to current user messaging_service: use separate set of connections per service levels replica/database: add reader concurrency semaphore groups qos: manage and assign scheduling groups to service levels qos: use the shares field in service level reads/writes qos: add shares to service_level_options qos: explicitly specify columns when querying service level tables db/system_distributed_keyspace: add shares column and upgrade code db/system_keyspace: adjust SL schema for workload prioritization gms: introduce WORKLOAD_PRIORITIZATION cluster feature build: increase the max number of scheduling groups qos: return correct error code when SL does not exist
ScyllaDB Documentation
This repository contains the source files for ScyllaDB Open Source documentation.
- The
devfolder contains developer-oriented documentation related to the ScyllaDB code base. It is not published and is only available via GitHub. - All other folders and files contain user-oriented documentation related to ScyllaDB Open Source and are sources for opensource.docs.scylladb.com.
To report a documentation bug or suggest an improvement, open an issue in GitHub issues for this project.
To contribute to the documentation, open a GitHub pull request.
Key Guidelines for Contributors
- The user documentation is written in reStructuredText (RST) - a plaintext markup language similar to Markdown. If you're not familiar with RST, see ScyllaDB RST Examples.
- The developer documentation is written in Markdown. See Basic Markdown Syntax for reference.
- Follow the ScyllaDB Style Guide.
To prevent the build from failing:
-
If you add a new file, ensure it's added to an appropriate toctree, for example:
.. toctree:: :maxdepth: 2 :hidden: Page X </folder1/article1> Page Y </folder1/article2> Your New Page </folder1/your-new-article> -
Make sure the link syntax is correct. See the guidelines on creating links
-
Make sure the section headings are correct. See the guidelines on creating headings Note that the markup must be at least as long as the text in the heading. For example:
---------------------- Prerequisites ----------------------
Building User Documentation
Prerequisites
- Python
- poetry
- make
See the ScyllaDB Sphinx Theme prerequisites to check which versions of the above are currently required.
Mac OS X
You must have a working Homebrew in order to install the needed tools.
You also need the standard utility make.
Check if you have these two items with the following commands:
brew help
make -h
Linux Distributions
Building the user docs should work out of the box on most Linux distributions.
Windows
Use "Bash on Ubuntu on Windows" for the same tools and capabilities as on Linux distributions.
Building the Docs
- Run
make previewto build the documentation. - Preview the built documentation locally at http://127.0.0.1:5500/.
Cleanup
You can clean up all the build products and auto-installed Python stuff with:
make pristine
Information for Contributors
If you are interested in contributing to Scylla docs, please read the Scylla open source page at http://www.scylladb.com/opensource/ and complete a Scylla contributor agreement if needed. We can only accept documentation pull requests if we have a contributor agreement on file for you.
Third-party Documentation
-
Do any copying as a separate commit. Always commit an unmodified version first and then do any editing in a separate commit.
-
We already have a copy of the Apache license in our tree, so you do not need to commit a copy of the license.
-
Include the copyright header from the source file in the edited version. If you are copying an Apache Cassandra document with no copyright header, use:
This document includes material from Apache Cassandra.
Apache Cassandra is Copyright 2009-2014 The Apache Software Foundation.