FreeBSD 4.9 losing mbufs!!!

[Stephen Clark]

Robert Watson wrote:

>On Tue, 18 Apr 2006, Stephen Clark wrote:
>
>  
>
>>I have discovered that if I disable quaqqa/ospfd then I don't lose mbufs! 
>>This makes it appear that the mbuf leak is in the multicast routing logic. 
>>In fact I lose mbufs even with the both system basically idle but with a 100 
>>vpn/gre with multicast going on thru the gre then the vpn.
>>
>>Any ideas on where to focus my continued investigation?
>>
>>Thanks to everybody who has responded.
>>    
>>
>
>Steve,
>
>Sorry not to have caught this thread earlier; I've been on travel for the last 
>few weeks.  My general suggestion would be to try to narrow the code paths 
>traversed to try to eliminate as much code as possible from the search.  It 
>sounds like you've done that pretty effectively :-).
>
>Typically, memory leaks occur in edge error cases, where the memory is not 
>properly released, or ownership is unclear.  My suggestion would be to add 
>counters (or look at existing counters where already present) and see if 
>there's an error case being triggered in about the same quantity that mbuf 
>leakage is occuring.  Chances are, there's an error being returned and a 
>missing m_freem().
>
>Based on your comments above, I might also pay attention to the routing socket 
>path -- the rate of leak could correspond to the routing daemons talking to 
>the network stack, rather than the rate of traffic.  For example, it could be 
>that one of the routing messages is handled improperly resulting in a leak.
>
>Unfortunately, tracking down memory leaks can be quite difficult, and tends to 
>require a combination of dogged persistence and luck...
>
>Robert N M Watson
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>
>  
>
Good news and bad news.

I managed to get enough of our system running on 6.x stable to test and 
it does not appear to lose mbufs. Bad news my ipsec transfer rate 
dropped from 54mbits/sec to 39mbits/sec. We need to be able to handle a 
t3 (45mbits/sec). Any ideas as to why this drop off in 6.x?

Steve

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