Hello Andrew, On Fri, Oct 22, 2010 at 12:20:50AM +0100, Andrew Murray wrote: > I'm performing some research [for a CELF presentation] into reducing > boot time on embedded systems and would like to see if the embedded > community agree with the following statement as to why Linux > [arguably] takes so long in the first place for an unoptimised system: > > "Linux is general purpose, convenient and flexible. As it's general > purpose it's likely to contain un-required functionality which results > in more initialisation and a larger image size. As it's convenient and > flexible it will spent time discovering devices and verifying their > existence." > > Do you largely agree or disagree? Also do you believe that boot time > isn't the highest priority when it comes to improving the kernel? I second what the others have already written. With a resonably tuned system it is possible to gain boot times of < 0.5 s into the Linux userspace on a 532 MHz MX35 (ARM1136). What highly matters if the use case, which in turn influences what can be done to decrease the boot time. - If a distribution is tuned to "run everywhere", it has to do a lot of probing, which needs time (i.e. a general purpose distribution on an ARM or PowerPC). In turn, you can easily install almost everything on such a system - If a system can be optimized for a special scenario (i.e. a machine operator terminal), you can configure away almost all unrequired functionality. In turn, it may be difficult to install random software parts on such a system. It's more a matter of paradigms. I assume we'll have nice boot time discussons at ELC-E, I also have a talk there concering this topic :-) 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 | -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
