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Re: Performance problem with route cache ?

To: "dada1" <dada1@xxxxxxxxxxxxx>
Subject: Re: Performance problem with route cache ?
From: Robert Olsson <Robert.Olsson@xxxxxxxxxxx>
Date: Fri, 21 Nov 2003 10:37:56 +0100
Cc: "Robert Olsson" <Robert.Olsson@xxxxxxxxxxx>, <netdev@xxxxxxxxxxx>, <scott.feldman@xxxxxxxxx>
In-reply-to: <037d01c3b004$86b78e00$890010ac@edumazet>
References: <02da01c3af54$c1f37f20$890010ac@edumazet> <16316.46493.7576.116171@robur.slu.se> <037d01c3b004$86b78e00$890010ac@edumazet>
Sender: netdev-bounce@xxxxxxxxxxx
dada1 writes:

 > Instead of using 2K or 4K buffers to store the data into socket, we end up
 > using 64 bytes size buffers... quite a huge difference indeed.
 > In case of a spike in network, the machine no longer consume 200 MB of
 > lowmem and stay alive.

 Well have no experice here... but think e1000 was using 4k for 1500 MTU
 packets at least before.

 > In a router context, copybreak should not be used, because the extra copy is
 > CPU intensive, and the data should not live long enough on memory.

 It easy to try again. I'm playing with realtek r8169 driver and are filling
 the skb one-by-one now as they are passed onto the stack. Rather than doing
 the RX-batch refill. I need to collect some data...
 
 > The machine just receives a lot of frames from a lot of different IP. That
 > is not a DOS attack.

 > rtstat -i 1
 >  size   IN: hit     tot    mc no_rt bcast madst masrc  OUT: hit     tot
 > mc GC: tot ignored goal_miss ovrf HASH: in
 > _search out_search
 > 279536      1490   11719     0     0     0     0     0       231     843
 > 0   12562   12560         2    0

 Well not DoS? What is this? See you have almost 10 times more new entries
 per/sec then what hits your already huge dst-cache. (hit/total).

 Compare to a procduction router for 10:th of thousands of users at 55 kpps.

size   IN: hit     tot    mc no_rt bcast madst masrc  OUT: hit     tot     mc 
GC: tot ignored goal_miss ovrf HASH: in_search out_search
21797     54543     529     0    49     0     0     0       137      12      0  
     0       0         0    0           28139         59

Cheers.
                                                        --ro

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