Caution

You're viewing documentation for a previous version of ScyllaDB Enterprise. Switch to the latest stable version.

ScyllaDB Docs ScyllaDB Enterprise ScyllaDB for Administrators Admin Tools Seastar Perftune

Seastar Perftune¶

ScyllaDB’s Seastar Perftune helps you run ScyllaDB with its maximum performance. The perftune.py script handles network and disk tuning, reassigning IRQs to specific CPU cores and freeing the other cores for ScyllaDB’s exclusive use.

More specifically, running the script will:

Ban relevant IRQs from being moved by irqbalance.
Configure various system parameters in /proc/sys.
Distribute the IRQs (using SMP affinity configuration) among CPUs according to the irq_cpu_mask value. Note that more than one physical core will be used for IRQ handling for large machines.

To ensure that the tuning persists after a host reboot, we recommend creating a systemd unit that will run on host startup and re-tune the hosts.

perftune.yaml¶

The perfrune.yaml file is the output file of the perftune.py script (with the --dump-options-file option enabled). The script determines the irq_cpu_mask and prints it to perftume.yaml on the first machine.

It’s important to use the same irq_cpu_mask value on other machines, even if more machines are added to the cluster, to avoid a mixed-cluster situation.

Note that perftune.yaml is generated only if the file doesn’t exist.

Available Options¶

You can run perftune.py with the following options:

Option	Description
`--arfs`	Enables/disables aRFS.
`--cpu-mask`	The masks of cores to use. The default is all available cores.
`--dev`	Specifies the device to optimize; for example, `sda1`. You can use it more than once to specify multiple devices.
`--dir`	Specifies the directory to optimize. You can use it more than once to specify multiple directories.
`--dry-run`	Prints recommendations on what to do without taking any action.
`--dump-options-file`	Prints the configuration YAML file containing the current configuration.
`--get-cpu-mask`	Prints the CPU mask to be used for computation.
`--get-cpu-mask-quiet`	Prints the CPU mask to be used for computation. Prints the zero CPU set if that’s what it is.
`--get-irq-cpu-mask`	Prints the CPU mask to be used for IRQs binding.
`--irq-core-auto-detection-ratio`	Specifies a ratio for IRQ mask auto-detection. For example, if 8 is given and auto-detection is requested, a single IRQ CPU core is going to be allocated for every 8 CPU cores out of available according to the `cpu_mask` value. The default is 16.
`--irq-cpu-mask`	The mask of the cores to be used for IRQs binding.
`--nic`	The network interface name. The default is `eth0`. You can use it more than once to specify multiple interfaces.
`--num-rx-queues`	Sets a given number of Rx queues.
`--options-file`	The configuration YAML file.
`--tune`	Specifies the components to configure. You can use it more than once to specify multiple values. The available values are: `net` - Enables tuning the network. `disks` - Enables tuning the disks. `system` - Enables tuning system-related components.
`--tune-clock`	Forces tuning of /system/clocksource. The default is `false`. Requires the `--tune` option.
`--verbose`	Provides additional details about operations and their results.
`--write-back-cache`	Enables/disables the write back write cache mode.

Was this page helpful?