Re: [PATCH 1/8] block: limit default readahead size for small devices

[Andi Kleen]

On Mon, Nov 21, 2011 at 05:00:04AM -0500, Christoph Hellwig wrote:
> On Mon, Nov 21, 2011 at 05:18:20PM +0800, Wu Fengguang wrote:
> > Given that the non-rotational attribute is not always reported, we can
> > take disk size as a max readahead size hint. This patch uses a formula
> > that generates the following concrete limits:
> 
> Given that you mentioned the rotational flag and device size in this
> mail, as well as benchmarking with an intel SSD  -  did you measure
> how useful large read ahead sizes still are with highend Flash device
> that have extremly high read IOP rates?

The more the IOPs the larger the "window" you need to keep everything
going I suspect.

-Andi
-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/