Re: Getting/Forcing Greater than 4KB Buffer Allocations

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