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Re: Route cache performance under stress

To: sim@xxxxxxxxxxxxx
Subject: Re: Route cache performance under stress
From: "David S. Miller" <davem@xxxxxxxxxx>
Date: Thu, 22 May 2003 01:58:15 -0700 (PDT)
Cc: netdev@xxxxxxxxxxx, linux-net@xxxxxxxxxxxxxxx, kuznet@xxxxxxxxxxxxx
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Sender: netdev-bounce@xxxxxxxxxxx
   From: Simon Kirby <sim@xxxxxxxxxxxxx>
   Date: Thu, 22 May 2003 01:40:03 -0700

     9631 handle_IRQ_event                          60.1938

Are you using APIC irqs?

    26552 fn_hash_lookup                            92.1944
   Hmm!  I guess the routing table size has a slight difference on
   performance there.

I assume you have CONFIG_IP_ROUTE_LARGE_TABLES enabled.

If not, try with that turned on.   If you had it on or enabling
it makes little difference, it is time to play with FZ_MAX_DIVISOR
and fn_hash().

All of your BGP routes have the same prefix right?  Yes, with ~181000
routes which you have fib zone hash in current state will fall to
pieces I am afraid.  (even with perfect hash, chain length would be
on the order of ~180 entries :-((( )

   I'm not sure if this is a "good" profile or not... I can try with
   oprofile or something instead if that gives more useful results.
It is good, thanks.

Alexey, I will try to make something...

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