[U-Boot] (no subject)

[U-Boot] (no subject)

[POLETTE Simon]

Hi,

I'm searching ways to get embedded Linux boot as fast as possible.
I'm working mainly on the kernel, but I have also to search means to optimize the bootloader.
so I'm looking for some leads that could make u-boot load the kernel faster.
Hope you could share your knowledge with me.
Thanks in advance.

Best regards,

Simon Polette

[U-Boot] (no subject)

[Wolfgang Denk]

Dear "POLETTE Simon",

In message <51D9710FF5643747BB605F97B8DE56CD0231C16C@STEGOSAURE.adetel.com> you wrote:
> 
> I'm searching ways to get embedded Linux boot as fast as possible.
> I'm working mainly on the kernel, but I have also to search means to
> optimize the bootloader.
> so I'm looking for some leads that could make u-boot load the kernel
> faster.

How much time does U-Boot need on your system to load the kernel?

And much is this compared to al the other times needed to boot your
system (in percent) ?

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
"A little knowledge is a dangerous thing."                - Doug Gwyn

[U-Boot] RE : Reduce time to load

[POLETTE Simon]

U-boot take about 2 seconds to load the kernel.
The rest of the system take about 10 seconds until I get the prompt, so it represents ~16% of total time needed to have an operational system.
I agree to say that most of the work to reduce boot time have to be done on the kernel and userspace, but I'm trying to save as much time as possible, even if it's 100ms.
Thanks a lot for your help.

Best regards,

Simon Polette



-------- Message d'origine--------
De: Wolfgang Denk [mailto:wd at denx.de]
Date: jeu. 26/02/2009 12:36
?: POLETTE Simon
Cc: u-boot at lists.denx.de
Objet : Re: [U-Boot] (no subject)
 
Dear "POLETTE Simon",

In message <51D9710FF5643747BB605F97B8DE56CD0231C16C@STEGOSAURE.adetel.com> you wrote:
> 
> I'm searching ways to get embedded Linux boot as fast as possible.
> I'm working mainly on the kernel, but I have also to search means to
> optimize the bootloader.
> so I'm looking for some leads that could make u-boot load the kernel
> faster.

How much time does U-Boot need on your system to load the kernel?

And much is this compared to al the other times needed to boot your
system (in percent) ?

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
"A little knowledge is a dangerous thing."                - Doug Gwyn

[U-Boot] RE : Reduce time to load

[Wolfgang Denk]

Dear Simon,

In message <51D9710FF5643747BB605F97B8DE56CD0231C16E@STEGOSAURE.adetel.com> you wrote:
> 
> U-boot take about 2 seconds to load the kernel.

That sounds resonable, depending on the device you load Linux from.

> The rest of the system take about 10 seconds until I get the prompt, so

10 seconds is a lot. I bet you use slow and/or big root file system, then.

And how long does it take to start the real application, then?

> it represents ~16% of total time needed to have an operational system.
> I agree to say that most of the work to reduce boot time have to be done
> on the kernel and userspace, but I'm trying to save as much time as
> possible, even if it's 100ms.

Well, trace the execution (for example by simply timestamping the
messages printed by U-Boot - expect comes in handy to do that), and
find out which poarts in U-Boot contribute most to these 2 seconds.

The old rules that always apply are: you can trade off reliability
for speed (like switching off image checksumming by setting the
"verify" variable to "no"), and you can trade off cose (like flash
memory foorprint) for speed (like using an uncompressed ext2 file
system in a MTD device, preferrably on NOR flash). See the DULG for
root file system selection, etc.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
A committee is a group that keeps the minutes and loses hours.
                                                      -- Milton Berle

[U-Boot] RE?: Reduce time to load

[Minkyu Kang]

And this patch will help you.

http://www.mail-archive.com/u-boot at lists.denx.de/msg09232.html
or
http://www.mail-archive.com/u-boot at lists.denx.de/msg09796.html

--
Minkyu Kang
from. prom.
promsoft.net