Re: [PATCH] preset loops_per_jiffy for faster booting

[Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl>]

Hi,

On Tuesday 13 of July 2004 00:41, Tim Bird wrote:
> Adam Kropelin wrote:
> > On Mon, Jul 12, 2004 at 11:52:44AM -0700, Tim Bird wrote:
> >>Adam Kropelin wrote:
> >>>Here's a patch. It places the relevant information on the same line as
> >>>bogomips and does so without encouraging anyone to fiddle with
> >>>loops_per_jiffy and screw up their kernel.
> >>
> >>The patch is missing the Kconfig piece.  Is the wording the
> >>same as from your earlier patch?
> >
> > Andrew requested that the config option be removed, so there are no
> > longer any changes to Kconfig.
>
> Oh - I missed the change where preset_lpj is no longer initialized
> from CONFIG_PRESET_LPJ.  I see it now.  I saw the comment from
> Andrew, but thought he was talking about the first version of the
> patch that had ifdefs.
>
> Here's what Andrew Morton said:
> > a) I don't see much point in making it configurable.  Just add the boot
> >    option and be done with it.  The few hundred bytes of extra code will
> > be dropped from core anyway.
> >
> >    The main reason for this is that most people won't turn on the config
> >    option, so your new code could get accidentally broken quite easily.
> >    Plus it removes some ifdefs.
>
> I have one or two arguments in favor of keeping the config option.
> First, for embedded systems it is sometimes necessary to compile-in
> the value. Unfortunately, not all architectures allow the
> kernel command line to be compiled in. (It would be nice if they did,
> but that's something to fix separately.)

Many do (i.e. arm, h8300, mips, ppc, sh) and IMHO it is better
to fix it separately where needed.

> The first restructuring of the patch that you did, I think addresses
> the issues that Andrew raised.  There are now no ifdefs, and since the
> core code doesn't drop away (and indeed can be turned on at boot time
> if needed), I think the code is not susceptible to accidental breakage
> like the first version was.  I think Andrew is right that the preset
> code path won't get much testing outside of embedded circles, so it is
> important that it be as simple as possible.
>
> The only *code* change from the configurable to the config-less version
> of the code is:
>
> +static unsigned long preset_lpj = CONFIG_PRESET_LPJ;
>    vs.
> +static unsigned long preset_lpj;

with the latter statement 'preset_lpj' ends up in BSS instead of data section
;-)

> Secondly, I was hoping to get the FASTBOOT menu in the kernel, because
> CELF has a few more patches to submit that have the same theme as this
> one.  (I realize this is not justification for making this option
> configurable, per se.  If we need to push for this on a subsequent patch,
> that's OK.)

Separate patch please if/when needed.