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74 lines
2.4 KiB
Markdown
74 lines
2.4 KiB
Markdown
honpey is tranlating
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How to Change Linux I/O Scheduler
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==================================
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Linux I/O Scheduler is a process of accessing the block I/O from storage volumes. I/O scheduling is sometimes called disk scheduling. Linux I/O scheduler works by managing a block device’s request queue. It selects the order of requests in the queue and at what time each request is sent to the block device. Linux I/O Scheduler manages the request queue with the goal of reducing seeks, which results in great extent for global throughput.
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There are following I/O Scheduler present on Linux:
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1. noop – is often the best choice for memory-backed block devices
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2. cfq – A fairness-oriented scheduler. It tries to maintain system-wide fairness of I/O bandwidth.
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3. Deadline – A latency-oriented I/O scheduler. Each I/O request has got a deadline assigned.
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4. Anticipatory – conceptually similar to deadline, but with more heuristics to improve performance.
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To View Current Disk scheduler:
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```
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# cat /sys/block/<Disk_Name>/queue/scheduler
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```
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Let’s assume that , disk name is /dev/sdc, type:
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```
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# cat /sys/block/sdc/queue/scheduler
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noop anticipatory deadline [cfq]
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```
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### To change Linux I/O Scheduler For A Hard Disk:
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To set a specific scheduler, simply type below command:
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```
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# echo {SCHEDULER-NAME} > /sys/block/<Disk_Name>/queue/scheduler
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```
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For example,to set noop scheduler, enter:
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```
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# echo noop > /sys/block/sdc/queue/scheduler
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```
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The above change is valid till reboot of the server , to make this change permanent across reboot follow below procedure:
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Implement permanent setting by adding “elevator=noop” to the default para in the /boot/grub/menu.lst file
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#### 1. Create backup of menu.lst file
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```
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cp -p /boot/grub/menu.lst /boot/grub/menu.lst-backup
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```
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### 2. Update /boot/grub/menu.lst
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Now add “elevator=noop” at the end of the line as below:
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Example
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```
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kernel /vmlinuz-2.6.16.60-0.91.1-smp root=/dev/sysvg/root splash=silent splash=off showopts elevator=noop
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```
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--------------------------------------------------------------------------------
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via: http://linuxroutes.com/change-io-scheduler-linux/
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作者：[UX Techno][a]
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译者：[译者ID](https://github.com/译者ID)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]:http://linuxroutes.com/change-io-scheduler-linux/
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