Difference between revisions of "IO Scheduler"
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(→Set IO Schedulers permanently: GRUB_CMDLINE_LINUX > GRUB_CMDLINE_LINUX_DEFAULT) |
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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. | ||
| Line 5: | Line 5: | ||
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 | ||
| Line 13: | Line 13: | ||
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: | ||
| Line 23: | Line 23: | ||
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: | ||
| Line 29: | Line 29: | ||
nano /etc/default/grub | nano /etc/default/grub | ||
| − | GRUB_CMDLINE_LINUX_DEFAULT="elevator=deadline" | + | GRUB_CMDLINE_LINUX_DEFAULT="... elevator=deadline" |
or: | or: | ||
| − | GRUB_CMDLINE_LINUX_DEFAULT="elevator=cfq" | + | GRUB_CMDLINE_LINUX_DEFAULT="... elevator=cfq" |
After you change /etc/default/grub you need to run update-grub to apply changes: | After you change /etc/default/grub you need to run update-grub to apply changes: | ||
| Line 39: | Line 39: | ||
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: | + | [[Category: HOWTO]] [[Category:System Administration]] |
Revision as of 10:11, 5 October 2016
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