| 2009-06-21 13:34:58 |
Cleber Santz |
description |
When install Linux in SSD Drives ( EeePC, pendrive, etc ) or Virtual machines the default Linux I/O scheduler ( CFQ ) make disk access very slower, causing sometimes system/application freeze.
If the scheduler is changed to NOOP the access to disk have a big improvement :
Kernel compilation
CFQ : 4161 seconds
NOOP: 3653 seconds ( 17% faster )
Link: http://www.alphatek.info/2009/02/02/ssd-performance-vs-linux-kernel-io-scheduler-in-fedora-10/
"The NOOP scheduler is a simple FIFO queue and uses the minimal amount of CPU/instructions per I/O to accomplish the basic merging and sorting functionality to complete the I/O. It assumes performance of the I/O has been or will be optimized at the block device (memory-disk) or with an intelligent HBA or externally attached controller."
Link: http://www.redhat.com/magazine/008jun05/features/schedulers/
But, the most end-users don't know about this option/tunning and will very helpful automatic add "elevator=noop" to kernel initialization when ubiquity is installing Ubuntu in this devices. |
When install Linux in SSD Drives ( EeePC, pendrive, etc ) or Virtual machines the default Linux I/O scheduler ( CFQ ) make disk access very slower, causing sometimes system/application freeze.
If the scheduler is changed to NOOP the access to disk have a big improvement :
Kernel compilation
CFQ : 4161 seconds
NOOP: 3653 seconds ( 13% faster )
Link: http://www.alphatek.info/2009/02/02/ssd-performance-vs-linux-kernel-io-scheduler-in-fedora-10/
"The NOOP scheduler is a simple FIFO queue and uses the minimal amount of CPU/instructions per I/O to accomplish the basic merging and sorting functionality to complete the I/O. It assumes performance of the I/O has been or will be optimized at the block device (memory-disk) or with an intelligent HBA or externally attached controller."
Link: http://www.redhat.com/magazine/008jun05/features/schedulers/
But, the most end-users don't know about this option/tunning and will very helpful automatic add "elevator=noop" to kernel initialization when ubiquity is installing Ubuntu in this devices. |
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