On Tue, Feb 08, 2011 at 09:39:25AM +0300, Alexander V. Lukyanov wrote:
> Hello!
>
> I cannot disable inode-read-ahead feature of ext4 (on 2.6.37):
>
> # echo 0 > /sys/fs/ext4/sda2/inode_readahead_blks
> bash: echo: write error: Invalid argument
>
> On a server with lots of small files and random access this read-ahead makes
> performance worse, and I'd like to disable it. I work around this problem
> by using value of 1, but it still reads an extra block.
So I'm curious --- have you actually benchmarked a performance
decrease? What sort of hardware are you using?
The readahead should be changing a 4k read to a 8k read with a value
of 1, which shouldn't take a much of a difference to a HDD.
I can apply this patch, but is it really making a difference for you?
- Ted
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