Re: New fast(?)-boot results on ARM

Robert Schwebel
2009-08-14T21:15:47Z

On Fri, Aug 14, 2009 at 11:01:58PM +0200, Linus Walleij wrote:
> >> > That's factor 70 away from the 110 ms boot time Tim has talked about
> >> > some days ago (and he measured on an ARM cpu which had almost half
> >> > the speed of this one), and I'm wondering what we can do to improve
> >> > the boot time.
> >>
> >> 2.4s in uncompression? That seems like an obvious target for
> >> improvement.
> >
> > Indeed, we'll check that.
>
> We got rid of uncompression on a flash-based system vastly improving
> boot time. The reason is that compressed kernels are faster only when
> the throughput to the persistent storage is lower than the decompression
> throughput, and on typical embedded systems with DMA the throughput to
> memory outperforms the CPU-based decompression.
>
> Of course it depends on a lot of stuff like performance of flash controller,
> kernel storage filesystem performance, DMA controller performance,
> cache architecture etc so it's individual per-system.

We have also done that on NOR based systems, but I'm not sure if it will
work out for NAND as well.

Thanks,

rsc
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |