IO Scheduler: Difference between revisions
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= Introduction | == Introduction == | ||
The Linux kernel, the core of the operating system, is responsible for controlling disk access by using kernel IO scheduling. | The Linux kernel, the core of the operating system, is responsible for controlling disk access by using kernel IO scheduling. | ||
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This article explains how-to change the IO scheduler without recompiling the kernel and without restart. | This article explains how-to change the IO scheduler without recompiling the kernel and without restart. | ||
= Check the currently used IO scheduler | == Check the currently used IO scheduler == | ||
cat /sys/block/sda/queue/scheduler | cat /sys/block/sda/queue/scheduler | ||
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Proxmox VE uses deadline by default, delivers best performance on hardware raid and SAN environments. | Proxmox VE uses deadline by default, delivers best performance on hardware raid and SAN environments. | ||
= 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 Deadline: | ||
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echo cfq > /sys/block/sda/queue/scheduler | echo cfq > /sys/block/sda/queue/scheduler | ||
= Set IO Schedulers permanently | == Set IO Schedulers permanently == | ||
In order to choose a new default scheduler you need to add the following into your /etc/default/grub: | In order to choose a new default scheduler you need to add the following into your /etc/default/grub: | ||
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update-grub | update-grub | ||
= Links = | == Links == | ||
*http://en.wikipedia.org/wiki/Deadline_scheduler | *http://en.wikipedia.org/wiki/Deadline_scheduler | ||
*http://en.wikipedia.org/wiki/CFQ | *http://en.wikipedia.org/wiki/CFQ | ||
[[Category: HOWTO]][[Category: Installation]] | [[Category: HOWTO]] [[Category: Installation]] | ||
Revision as of 20:27, 26 October 2015
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
noop anticipatory [deadline] cfq
Proxmox VE uses deadline by default, delivers best performance on hardware raid and SAN environments.
Switching IO Schedulers on runtime
Set the scheduler for /dev/sda to Deadline:
echo deadline > /sys/block/sda/queue/scheduler
Set the scheduler for /dev/sda to CFQ:
echo cfq > /sys/block/sda/queue/scheduler
Set IO Schedulers permanently
In order to choose a new default scheduler you need to add the following into your /etc/default/grub:
nano /etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT="... elevator=deadline"
or:
GRUB_CMDLINE_LINUX_DEFAULT="... elevator=cfq"
After you change /etc/default/grub you need to run update-grub to apply changes:
update-grub