--- In Alexander Clouter <> wrote:
>
> Hi,
>
> Fabio Vaz <> [20080428 19:34:08 -0000]:
> >
> > I'm facing a problem with kernel 2.6.23. In my Ts-7200 with kernel
> > 2.4 the /proc/cpuinfo BogoMIPS shows 99.94. With Kernel 2.6 it shows
> > 49.86.
> >
> /me points at the *name*
>
> *BOGO*mips....as in bogus. An emphasis of
> Meaningless-Instructions-Per-Second. It's nothing but a timing loop
that the
> kernel uses for scheduling if I remember correctly.
>
> http://en.wikipedia.org/wiki/BogoMips
>
> > It must be something in the kernel slowing down the CPU for power
> > savings purposes. Do you know where can I find this ?
> >
> Check that thar t'internet for more information.
>
> I vaguely recall somewhere in the middle of the 2.6 series things
halved...or
> doubled...or something.
Except in this case, it *is* a symptom of a real problem I found in
redboot quite some time ago. Your CPU *is* running half-speed. Apply
(and enable!) the following patch. It may already be in the patch set
you are using (I haven't checked); if so just enable it in your config.
Regards ......... Charlie
1) Set nF bit patch
Without this, your CPU will run at 100 MHz. May
be fixed in a future redboot release, but for now you need to patch
this and turn it on:
diff -ubr arm.orig/mach-ep93xx/Kconfig arm/mach-ep93xx/Kconfig
--- arm.orig/mach-ep93xx/Kconfig 2007-01-30 22:42:57.000000000
-0500
+++ arm/mach-ep93xx/Kconfig 2007-02-03 14:41:40.000000000 -0500
@@ -7,6 +7,15 @@
help
Enable kernel support for MaverickCrunch.
+config CR1_NFBIT
+ bool "Turn on nF bit in ControlRegister 1"
+ help
+ Say 'Y' here to force the nF bit on. Usually this is set
+ by the bootrom. If it is not set, then the CPU core will
+ run from HCLK instead of FCLK, and performance will suffer.
+ If you see BogoMIPS of about 1/4 of your CPU clock, try
+ turning this on; your performance should double.
+
comment "EP93xx Platforms"
config MACH_ADSSPHERE
diff -ubr arm.orig/mm/proc-arm920.S arm/mm/proc-arm920.S
--- arm.orig/mm/proc-arm920.S 2007-01-30 22:42:57.000000000 -0500
+++ arm/mm/proc-arm920.S 2007-02-03 14:29:00.000000000 -0500
@@ -395,6 +395,9 @@
mrc p15, 0, r0, c1, c0 @ get control register
v4
bic r0, r0, r5
orr r0, r0, r6
+#ifdef CONFIG_CR1_NFBIT
+ orr r0, r0, #0x40000000 @ set nF
+#endif
mov pc, lr
.size __arm920_setup, . - __arm920_setup
> Cheers
>
> Alex
>
> --
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> \ satisfaction brought her back. /
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