Re: [blockdevices/NBD] huge read/write-operations are splitted by the kernel

[Jens Axboe]

On Mon, Sep 08 2003, Sven Köhler wrote:
> >You'll probably find that if you bump the max_sectors count if your
> >drive to 256 from 255 (that is the default if you haven't set it), then
> >you'll see 128kb chunks all the time.
> 
> Why is 255 the default. It seems to be an inefficient value. Perhaps the 
> NBD itself should set it to 256.

To avoid 8-bit wrap arounds, basically. Not sure it's still very valid,
you are free to compile your kernel with it set to 256. 2.6 uses 256 by
default.

> >See max_sectors[] array.
> 
> Well, i found the declaration, but i can't imagine how to set the values 
> in it.

You can grep for other examples in the kernel, I would imagine?

-- 
Jens Axboe

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