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Date:      Sun, 04 Sep 2011 19:11:30 -0600
From:      Brett Glass <brett@lariat.net>
To:        Robert Bonomi <bonomi@mail.r-bonomi.com>
Cc:        questions@freebsd.org
Subject:   Re: Huge interrupt overhead reported after RAM added to Atom-based system
Message-ID:  <201109050111.TAA07025@lariat.net>
In-Reply-To: <201109042333.p84NXkiK002887@mail.r-bonomi.com>
References:  <201109041814.MAA04568@lariat.net> <201109042333.p84NXkiK002887@mail.r-bonomi.com>

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At 05:33 PM 9/4/2011, Robert Bonomi wrote:

>Does sound sorta-like VM thrashing.
>
>Could it be hardware based _bank-switching_ on memory?
>
>This would cause an intterrupt every time successive memory accesses were in
>differnt 'banks'.

Indeed. In fact, when you put in a 4GB module, the BIOS reports 
that you have 1GB of "4GB+ memory" (a possible indication that the 
last gigabyte is mapped into some special space). Maybe there's 
something like PAE going on. Anyone know what might be up? (Copying 
this message back to the list thread)

--Brett Glass 




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