Difference between revisions of "OS: Tuning Completely Fair Queueing CFQ I/O scheduler"

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Sumber: http://publib.boulder.ibm.com/infocenter/lnxinfo/v3r0m0/index.jsp?topic=%2Fliaai%2Fsaptuning%2Fsaptuningadjust.htm
 
Sumber: http://publib.boulder.ibm.com/infocenter/lnxinfo/v3r0m0/index.jsp?topic=%2Fliaai%2Fsaptuning%2Fsaptuningadjust.htm
  
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Completely Fair Queueing (CFQ) I/O scheduler mengatur komitmen bagaimana Linux kernel membaca dan menulis ke disk dan bekerja untuk mengoptimasi waktu akses ke disk.
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Completely Fair Queueing (CFQ) I/O scheduler mengatur komitmen bagaimana Linux kernel membaca dan menulis ke disk dan bekerja untuk mengoptimasi waktu akses ke disk. Tanpa I/O Scheduler, kernel akan langsung menjalankan setiap request pada saat di terima, dan ini akan menyebabkan kerusakan: jika satu proses membaca dari satu bagian dari disk, dan satu menulis pada bagian yang lain, head disk harus bergerak maju dan mundur menjelajahi disk untuk setiap operasi. Kta dapat menggunakan CFQ scheduler untuk mengontrol bagaimana kernel membaca dan menulis ke disk untuk menghindari kerusakan.
  
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Without an I/O scheduler, the kernel would issue each request in the order that it is received, resulting in thrashing: if one process reads from one part of the disk, and one writes to another, the heads would have to seek back and forth across the disk for every operation. You can use the CFQ scheduler to control how the kernel reads and writes to disks to avoid thrashing.
 
 
Note: Using other schedulers with the SAP SD workload in the test environment did not result in a performance gain.
 
Note: Using other schedulers with the SAP SD workload in the test environment did not result in a performance gain.
 
Ensure that CFQ is the I/O scheduler enabled on your system with the following command:
 
Ensure that CFQ is the I/O scheduler enabled on your system with the following command:

Revision as of 11:05, 31 March 2013

Sumber: http://publib.boulder.ibm.com/infocenter/lnxinfo/v3r0m0/index.jsp?topic=%2Fliaai%2Fsaptuning%2Fsaptuningadjust.htm

Completely Fair Queueing (CFQ) I/O scheduler mengatur komitmen bagaimana Linux kernel membaca dan menulis ke disk dan bekerja untuk mengoptimasi waktu akses ke disk. Tanpa I/O Scheduler, kernel akan langsung menjalankan setiap request pada saat di terima, dan ini akan menyebabkan kerusakan: jika satu proses membaca dari satu bagian dari disk, dan satu menulis pada bagian yang lain, head disk harus bergerak maju dan mundur menjelajahi disk untuk setiap operasi. Kta dapat menggunakan CFQ scheduler untuk mengontrol bagaimana kernel membaca dan menulis ke disk untuk menghindari kerusakan.

Note: Using other schedulers with the SAP SD workload in the test environment did not result in a performance gain. Ensure that CFQ is the I/O scheduler enabled on your system with the following command: 

# cat /sys/block/<device>/queue/scheduler
# noop anticipatory deadline [cfq]

where device is the name of the disk on which you want CFQ to run.

The brackets ([]) indicate the scheduler that is currently in effect. Or, you can change the assigned scheduler with the following command: 

# echo cfq > /sys/block/<device>/queue/scheduler

where device is the name of the disk on which you want to change the assigned scheduler.



Referensi

Pranala Menarik

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