linux-kernel - Re: linux-2.6.23

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Date:	Fri, 12 Oct 2007 00:53:19 +0200
From:	poison <rc.poison@...il.com>
To:	Helmut Toplizer <bgrpt@...litzer.net>
Cc:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>
Subject: Re: linux-2.6.23 - acting funny

Hi =)

On Thursday 11 October 2007, Helmut Toplizer wrote:
> Hi!
>
> I had similar behavior in the kernel releases since I can think of.
It doesn't happen before 2.6.23.

> (You may find some reports about at
> http://marc.info/?a=113508574400006&r=1&w=2)
>
> Maybe your problem is similar.
>
> Here's what have been found out:
> Plugin of ehci devices causes some strange DMA thing
> which causes delays because of the CPU HLT instruction.
> (DMA are handled with delays on HLT)
>
> Possible fixes:
> 1) Kernel parameter: idle=poll
>     Disables HLT and causes heat up and noise from the cpu
$ cat /proc/cmdline
root=/dev/sdb1 ro vga=794 idle=poll

Same story. 
If I start:
$ while true; do echo test > /dev/null; done
... the transfer rate goes up.

>
> 2) Don't insert EHCI-USB devices
Still reproducable with all USB devices except keyboard+mouse removed, ehci 
deselcted in kernel config and booting with idle=poll.

>
> 3) Patch: attached, try out at your own risk.
>     you need to add a kernel-boot parameter "disableviahlt"
>    (You've got a via-chipset, right?)
>
> Please report back to me if 1/2 works or to linux-ide if the patch works.
No VIA chip in sight. Mainboard is an Intel 975XBX2 and hard disks are 
connected to the ICH7 SATA Controller, so I don't think the patch will help 
me ^^
lspci attached.

Also the transfer rate didn't degrade too much for copying directly from 
reiserfs to reiserfs and not using encfs:

dd if=/mnt/.backup/2CpGkrxvz6wgA0b0xloz8PavzMLrMymOgi9 of=/mnt/.tdata/test
1033+0 records in
1033+0 records out
1083179008 bytes (1.1 GB) copied, 16.9303 s, 64.0 MB/s

Plus the transfer rate doesn't increase if I start a CPU hog while copying 
between reiserfs.

So it looks more to me like theres a bad interaction between the new 
scheduler, fuse and encfs ...


> Thanks
>
> Helmut

Thanks for your reply ^^

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