RE: PATA IDE is slower in newer versions of kernel

["Joshua Hintze" <joshh@imsar.com>]

I got you. 

Thanks.


-----Original Message-----
From: Randy Dunlap [mailto:rdunlap@xenotime.net] 
Sent: Saturday, September 18, 2010 1:48 PM
To: Joshua Hintze
Cc: 'Maxim Levitsky'; linux-kernel@vger.kernel.org;
linux-ide@vger.kernel.org
Subject: Re: PATA IDE is slower in newer versions of kernel

On Sat, 18 Sep 2010 13:43:40 -0600 Joshua Hintze wrote:

> Thanks,
> 
> I'm not sure what you mean by bisect, other than just the definition of
the word. I am breaking this problem down adding printks etc.  I think I'm
finally beginng to understand how this works :)
> 

http://www.kernel.org/pub/software/scm/git/docs/git-bisect.html
http://www.kernel.org/pub/software/scm/git/docs/user-manual.html#using-bisec
t


> 
> 
> -----Original Message-----
> From: linux-ide-owner@vger.kernel.org
[mailto:linux-ide-owner@vger.kernel.org] On Behalf Of Maxim Levitsky
> Sent: Saturday, September 18, 2010 1:23 PM
> To: Joshua Hintze
> Cc: linux-kernel@vger.kernel.org; linux-ide@vger.kernel.org
> Subject: RE: PATA IDE is slower in newer versions of kernel
> 
> On Sat, 2010-09-18 at 11:12 -0600, Joshua Hintze wrote:
> > Some updated information. I created a screen capture of what I am
seeing. First is the logic analyzer when the newer linux kernel is writing
slow to the PATA port.
> > 
> > http://i56.tinypic.com/oqhrug.png
> > 
> > Notice in the above link how there is a lot of activating and then large
gaps of no activity. After about 9 mS the STOP line is strobed a few times
and then DMARQ finally returns to normal operating. The link below shows the
picture of an old 2.6.10 kernel where write speeds are much faster.
> > 
> > http://i51.tinypic.com/a9wiur.png
> > 
> > In the above image notice how the wait time is considerable less 100's
of microseconds before the stop lines get strobed.
> > 
> > I'm dedicated to continue working on the problem, I just need to advice
from the linux community. I've tried different I/O schedulers such as noop
and anticipatory and I'm studying the ide-dma code but still lost to where
this is happening.
> > 
> > Thanks!
> > 
> Maybe you can just bisect this?
> Just a general advice, I don't know ide subsystem at all.
> 
> Best regards,
> 	Maxim Levitsky


---
~Randy
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