slow in user space?

slow in user space?

[John Ma]

Hi all,
    I have a MPC8241 board and  running ppc kernel 2.4.21-pre7 on it.
Serial console is enabled and a small ramdisk is mounted as root.  The
board is running at 200M Hz.  The kernel seems to be ok during bootup
(just a few seconds).  But after the root filesystem is mounted and
/sbin/init is started, the system becomes very slow.  I need to wait
several minutes for the login console.
    My board has no rtc.  So I assume that tb_ticks_per_jiffy is equal
to be 25M/HZ (25M is the memory clock frequency).  tb_ticks_per_jiffy
will set the decrementer register which will control how long the timer
interrupt occurs.  is it correct to set this value?
    I have ever tried some smaller values for it and I found that the
speed becomes faster.  But the time on the board becomes faster also
(uptime on the board is several hours but I power on it just several
minutes).
    Does anyone have suggestions on it?

Thanks.

Best Regards
John


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Re: slow in user space?

[Dan Malek]

John Ma wrote:

>    I have a MPC8241 board and  running ppc kernel 2.4.21-pre7 on it.


> ....But after the root filesystem is mounted and
> /sbin/init is started, the system becomes very slow.  I need to wait
> several minutes for the login console.

Your DUART interrupts aren't routed/initialized correctly.  The serial
driver has timeouts that slowly poll the driver if interrupts aren't
showing up.


	-- Dan


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Re: slow in user space?

[bhupinder sahran]

Hi
>From the inputs u have given, looks like Interrupt are
nor settled properly. After mounting the ramdisk
console driver (serial port in ur case)starts working
in interrupt mode. If serial port interrupt are not
set properly, It will work on timer based & system
will be slow.

It may help......................

Bhupi
www.gdatech.com
Linux+Hypertransport -> Silicon
www.gdatech.com
Good after beer -- Linux

--- John Ma <kwma@avantwave.com> wrote:
>
> Hi all,
>     I have a MPC8241 board and  running ppc kernel
> 2.4.21-pre7 on it.
> Serial console is enabled and a small ramdisk is
> mounted as root.  The
> board is running at 200M Hz.  The kernel seems to be
> ok during bootup
> (just a few seconds).  But after the root filesystem
> is mounted and
> /sbin/init is started, the system becomes very slow.
>  I need to wait
> several minutes for the login console.
>     My board has no rtc.  So I assume that
> tb_ticks_per_jiffy is equal
> to be 25M/HZ (25M is the memory clock frequency).
> tb_ticks_per_jiffy
> will set the decrementer register which will control
> how long the timer
> interrupt occurs.  is it correct to set this value?
>     I have ever tried some smaller values for it and
> I found that the
> speed becomes faster.  But the time on the board
> becomes faster also
> (uptime on the board is several hours but I power on
> it just several
> minutes).
>     Does anyone have suggestions on it?
>
> Thanks.
>
> Best Regards
> John
>
>
>


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