[G2 Q&A, Help & Troubleshooting] bloof:
I/O SCHEDULER​

I don't actually know much about this, so will just repeat what I see elsewhere. However, all tests I have done were not as conclusive as I would have hope.

This will not change your life. Don't expect I/O scheduler to have any drastic effect on your phone experience unless you've been using a crappy one.

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SUMMARY:

ROW vs FIOPS:

FIOPS is better performance and battery but not for multitasking.

ROW is a very good balanced scheduler.

THERE ARE OTHER OPTIONS, see below.

What matters:

- external SD card or not

- multitasking or not

- whether you care about battery life or not

- your machine

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WHICH ONE TO SELECT?

I will link to someone else's work:

http://androidmodguide.blogspot.co.uk/p/io-schedulers.html

credit to the author, who I am sure is lurking around here in xda.

Please read his article.

Results (again, not mine):

Recommended IO schedulers:

For everyday usage:

- SIO (My personal favourite)

- NOOP

- CFQ (Third choice)

- Deadline (Forth choice)

- ROW (My second choice)

- ZEN

For battery life:

- SIO (First choice)

- FIOPS

- NOOP (Second choice)

- ROW (Third choice)

- FIFO

For gaming:

- Deadline (First choice)

- CFQ (Second choice)

- ROW (Third choice)

For performance(Benchmarking):

- VR

- SIO (Third Choice)

- Deadline (Second choice)

- FIOPS (First choice)

For multitasking:

- BFQ (Third choice)

- Deadline (Second choice)

- CFQ (First choice)

IO Scheduler Comparison:

Overall performance:

BestWorst

FIOPS> Noop > ZEN >SIOplus > SIO > ROW > Tripndroid > VR > Deadline > BFQ > CFQ

Multitasking performance:

Less AppsMany Apps

Noop < FIOPS < SIO < SIOplus < ROW < Tripndroid < ZEN < Deadline < VR < CFQ < BFQ

Battery life:

Best Worst

Noop > FIOPS > SIOplus > SIO > ROW> ZEN > Tripndroid > Deadline > VR > CFQ > BFQ

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Read-ahead:

http://andrux-and-me.blogspot.fr/2014/06/various-conditions-and-io-performance.html

The usual answers I see seem to indicate that you should leave at default, whatever your kernel maker seems to think is best.

Having too high a number can lead to issues if the I/O needs to read/write a lot of things on the fly with streaming going on and multitasking.

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Further Reading:

If you use google you will easily find a lot of material on I/O schedulers.

Here is a page with some descriptions and advantages/disadvantages: http://tinzdroid.blogspot.co.uk/2012/07/android-kernel-governors-modules-io.html

Another link: http://androidmodguide.blogspot.co.uk/p/io-schedulers.html