Re: PROBLEM: tickless scheduling

[Donald Allen]

On Wed, May 12, 2010 at 4:52 PM, john stultz <johnstul@xxxxxxxxxx> wrote:
> On Wed, 2010-05-12 at 15:54 -0400, Donald Allen wrote:
>> Before doing what you asked, I ran my home-brew backup script, which
>> tars up the whole machine, save my home directory, to a big sata drive
>> in a usb shoebox. I did so by booting the most recent Arch Linux
>> install/live CD (while I use Slackware, the Slackware install CDs are
>> not suitable for this sort of thing, having very old versions of
>> things like tar). While doing so, I observed exactly the same symptoms
>> I did with the Slackware 13.1 install, which I described in the bug
>> report. So rather than messing with the hard-won custom kernel that I
>> now have installed on the netbook, I am attaching the various things
>> from /proc gathered with the Arch kernel running. Yes, it's a somewhat
>> older kernel (2.6.30), but I'm hoping that things haven't changed much
>> in tickless land. If that's not the case, then I will attempt to
>> reproduce this with the newer kernel on the Slackware 13.1 install
>> DVD. Let me know if you need me to do this. The attached tar file is
>> bzip2-compressed, so you want xjf to extract.
>
> Hmm.. Sorry, but I have another quick request. Could you send
> your /proc/interrupts output from the kernel having the problem?

Attached. This is from the 2.6.30 kernel on the Arch Linux install cd.

Here's another bit of data. As I've said previously, the problems I'm
reporting were observed on a Toshiba NB310-305 netbook with a
single-core Atom 450 processor. I just built myself a mini-ITX system
using the Intel D510MO motherboard, which provides a dual-core D510
Atom processor. The other hardware on the board is similar to the
Toshiba. I installed the same Slackware snapshot I used on the
Toshiba, and did the home directory transfer without any problem at
all with the default tickless kernel. The hardware isn't identical,
and while I don't know the internals of the Linux kernel at all, my
gut, backed up by many years of OS development work in scheduling and
memory management, is telling me that the key difference is dual- vs.
single-core. Just a guess.

Hope this helps --

/Don

>
> thanks
> -john
>
>
>

Attachment: interrupts
Description: Binary data