[ovs-dev] [PATCH 2/2] Raise MAC learning table capacity from 1, 024 to 2, 048 entries per bridge.

Justin Pettit jpettit at nicira.com
Sun Sep 13 18:52:44 UTC 2009

On Sep 13, 2009, at 7:47 PM, Ben Pfaff wrote:

>> Even 2048 entries seems kind of low to me.  Look around on the web,  
>> 8K
>> entries seems pretty common in hardware switches.  A quick look in  
>> the
>> kernel sources at the bridge seems to indicate they have no limit
>> (which is worrying in its own right).
> Our current implementation of MAC learning statically allocates
> the entire MAC-learning table at a cost of about 40 kB per table.
> Doubling the number of entries to 2,048 makes them more like 80
> kB.  I'm nervous about increasing the limit to 8,192 which would
> make the cost 320 kB each.  Hence the comment about wanting to
> switch to dynamic memory allocation if we raise the limit any
> further.

Right, I understood that.  My point was that we may want to move more  
aggressively towards that than I felt was conveyed in the commit  
message.  This may be something that we want to do in the master  
branch before too long.


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