Re: [patch 6/7] ps3: ROM Storage Driver

From: Christoph Hellwig
Date: Wed May 30 2007 - 06:14:37 EST


On Tue, May 29, 2007 at 01:11:41PM +0200, Geert Uytterhoeven wrote:
> > This looks very inefficient. Just set sg_tablesize of your driver
> > to 1 to avoid getting mutiple segments.
>
> The disadvantage of setting sg_tablesize = 1 is that the driver will get small
> requests (PAGE_SIZE) most of the time, which is very bad for performance.

If you set .clustering = 1 in your host template you will frequently
get larger requests.

For any sane hypervisor or hardware the copy should be worth
than that. Then again a sane hardware or hypervisor would support
SG requests..

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