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Date:      Tue, 17 Jul 2007 17:14:36 -0700
From:      Chuck Swiger <cswiger@mac.com>
To:        David Christensen <davidch@broadcom.com>
Cc:        current@freebsd.org
Subject:   Re: Getting/Forcing Greater than 4KB Buffer Allocations
Message-ID:  <2E0C9A04-678B-4C44-9D2E-5500F2C08FE7@mac.com>
In-Reply-To: <09BFF2FA5EAB4A45B6655E151BBDD9030483F161@NT-IRVA-0750.brcm.ad.broadcom.com>
References:  <09BFF2FA5EAB4A45B6655E151BBDD9030483F161@NT-IRVA-0750.brcm.ad.broadcom.com>

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On Jul 17, 2007, at 4:54 PM, David Christensen wrote:
> I'm investigating a problem with my bce driver which occurs when I ask
> for a jumbo mbuf cluster (through m_cljget()).  When I map the  
> memory for DMA I
> normally get 3 memory segments (4KB + 4KB + 1KB) on my system, but  
> on another
> user's system he's seeing 2 memory segments (8KB + 1KB).  Is there a
> configurationoption that allows this or some other tuning variable  
> involved?  The
> system is a Xeon dual-core processor and has 8GB of RAM, running an  
> AMD64 version of
> the kernel.

Hi, Dave--

Is "sysctl hw.pagesize" different on the two systems?  It sure looks  
like the first machine is using a 4KB pagesize, whereas the second  
machine is using an 8KB pagesize...

-- 
-Chuck




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