IO Scheduler: Difference between revisions
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cat /sys/block/sda/queue/scheduler | cat /sys/block/sda/queue/scheduler | ||
[none] mq-deadline bfq | |||
For example the scheduler '''deadline''' delivers best performance on hardware raid and SAN environments. While ''' | For example the scheduler '''mq-deadline''' delivers best performance on hardware raid and SAN environments. While '''none''' delivers better performance for SSDs. | ||
If you don't see <code>bfq</code> as an option, it means that the kernel module is not loaded. It is still possible to configure the BFQ scheduler however, which will automatically load the kernel module. To load the module manually, use: | |||
modprobe bfq | |||
== Switching IO Schedulers on runtime == | == Switching IO Schedulers on runtime == | ||
Set the scheduler for /dev/sda to Deadline: | Set the scheduler for /dev/sda to Multi-Queue Deadline: | ||
echo deadline > /sys/block/sda/queue/scheduler | echo mq-deadline > /sys/block/sda/queue/scheduler | ||
Set the scheduler for /dev/sda to | Set the scheduler for /dev/sda to BFQ: | ||
echo | echo bfq > /sys/block/sda/queue/scheduler | ||
== Set IO Schedulers permanently == | == Set IO Schedulers permanently == | ||
This can be done via udev rules. For a basic example, create <code>/etc/udev/rules.d/60-io-scheduler.rules</code> with content: | |||
ACTION=="add|change", KERNEL=="sd[a-z]*", ATTR{queue/scheduler}="bfq" | |||
== Links == | == Links == | ||
* | *https://www.kernel.org/doc/html/v6.8/block/bfq-iosched.html | ||
* | *https://www.kernel.org/doc/html/v6.8/block/blk-mq.html | ||
*https://www.kernel.org/doc/html/v6.8/block/deadline-iosched.html | |||
*https://cromwell-intl.com/open-source/performance-tuning/disks.html | *https://cromwell-intl.com/open-source/performance-tuning/disks.html | ||
[[Category: HOWTO]] [[Category:System Administration]] | [[Category: HOWTO]] [[Category:System Administration]] | ||
Revision as of 11:56, 6 February 2025
Introduction
The Linux kernel, the core of the operating system, is responsible for controlling disk access by using kernel IO scheduling.
This article explains how-to change the IO scheduler without recompiling the kernel and without restart.
Check the currently used IO scheduler
cat /sys/block/sda/queue/scheduler
[none] mq-deadline bfq
For example the scheduler mq-deadline delivers best performance on hardware raid and SAN environments. While none delivers better performance for SSDs.
If you don't see bfq as an option, it means that the kernel module is not loaded. It is still possible to configure the BFQ scheduler however, which will automatically load the kernel module. To load the module manually, use:
modprobe bfq
Switching IO Schedulers on runtime
Set the scheduler for /dev/sda to Multi-Queue Deadline:
echo mq-deadline > /sys/block/sda/queue/scheduler
Set the scheduler for /dev/sda to BFQ:
echo bfq > /sys/block/sda/queue/scheduler
Set IO Schedulers permanently
This can be done via udev rules. For a basic example, create /etc/udev/rules.d/60-io-scheduler.rules with content:
ACTION=="add|change", KERNEL=="sd[a-z]*", ATTR{queue/scheduler}="bfq"