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Subject: RE: PATA IDE is slower in newer versions of kernel
From: Maxim Levitsky <maximlevitsky@gmail.com>
To: Joshua Hintze <joshh@imsar.com>
Cc: linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org
In-Reply-To: <010901cb5754$ae6735a0$0b35a0e0$@com>
References: <00d401cb55f7$33a78210$9af68630$@com>
	 <20100917154732.330c4b1b@varda>  <010901cb5754$ae6735a0$0b35a0e0$@com>
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Date: Sat, 18 Sep 2010 21:22:54 +0200
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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