linux-kernel - Re: Lower HD transfer rate with NCQ enabled?

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Message-ID: <4616BC95.8070009@tmr.com>
Date:	Fri, 06 Apr 2007 17:33:09 -0400
From:	Bill Davidsen <davidsen@....com>
To:	Paa Paa <paapaa125@...mail.com>
CC:	nickpiggin@...oo.com.au, linux-kernel@...r.kernel.org
Subject: Re: Lower HD transfer rate with NCQ enabled?

Paa Paa wrote:
>>> Q: What conclusion can I make on "hdparm -t" results or can I make 
>>> any conclusions? Do I really have lower performance with NCQ or not? 
>>> If I do, is this because of my HD or because of kernel?
>>
>> What IO scheduler are you using? If AS or CFQ, could you try with 
>> deadline?
> 
> I was using CFQ. I now tried with Deadline and that doesn't seem to 
> degrade the performance at all! With Deadline I got 60MB/s both with and 
> without NCQ. This was with "hdparm -t".
> 
> So what does this tell us?
> 
It suggests that it's time to test with real load and see if deadline 
works well for you in the general case.

-- 
Bill Davidsen <davidsen@....com>
   "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot
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