eh, this is really only good for benching, because otherwise we stop
traversing the pf ruleset for very short amounts of time if we are
about to exhaust CPU. this allows already established connections to
live on and the OP to log in to the box via console and take
countermeasures. if you already ahd an ssh sessionto teh box it has
good chances to survive and you can even take countermeasures over that.
what you really want to do for high speed routers is increasing
net.inet.ip.ifq.maxlen
I currently use 250 on some routers which seems good, but I need to do
more tests before I can make qualified assumptions about good values.
This is the max length of a queue in the input path, and the default of
50 packets is too small for high speed routers with modern GigE cards
that can put about that into teh queue with one single int. Or even more.
In the end I think we need a better default based on some factors like
ip forwarding enabled and summarized link speed and RAM in teh box or
somesuch. Ryan and I discussed that on the ferry earlier this year and
have some good ideas, now we just need some time to work on it ;(
* Schvberle Daniel <[EMAIL PROTECTED]> [2005-10-18 18:36]:
> Hi,
>
> I was trying to bench routing pps with pf on and henning gave me
> some advice which I think might help you too. For my benching purposes
> it helped break the 200k pps barrier with current but no guaranties
> that it'll do you any good or that it won't hurt you.
>
> <quote>
> The high drop rates
> are a anti-DDoS measure - yeah, that pretty much makes benching
> impossible...
> you could change IF_INPUT_ENQUEUE in sys/net/if.h so that it looks like
>
> #define IF_INPUT_ENQUEUE(ifq, m) { \
> if (IF_QFULL(ifq)) { \
> IF_DROP(ifq); \
> m_freem(m); \
> } else \
> IF_ENQUEUE(ifq, m); \
> }
>
> i. e. remove these two lines:
> if (!(ifq)->ifq_congestion) \
> if_congestion(ifq); \
>
> that means the congestion flag will never be set.
> or you add a return; as first statement in if_congestion() in if.c.
>
> <endquote>
>
> > -----Original Message-----
> > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> > On Behalf Of dormando
> > Sent: Monday, October 17, 2005 8:29 PM
> > To: misc@openbsd.org
> > Subject: Very high interrupts on a supermicro machine.
> >
> > Hey all,
> >
> > Attached is a dmesg of one of a pair of supermicro based firewalls I
> > recently bought. I had set them up as a CARP/pfsync redundant pair of
> > frontend firewalls for our network. However, after they reached 15,000
> > interrupts per second (~ 110 megabits of our site traffic),
> > they passed 90%
> > CPU usage through interrupts and stopped being useful.
> >
> > The machines have two built-in BGE nics. I swapped in an
> > Intel PRO/1000MT
> > Dual Port Server Nic into a PCI-X 133mhz PCI slot, but it
> > made absolutely no
> > difference in the interrupt load. The current firewalls in
> > place are freebsd
> > machines running on supermicro hardware with two em based
> > built-in nics
> > running past 40k interrupts without passing 50% CPU load on
> > interrupts. The
> > only error I can see in the dmesg was this:
> >
> > pcibios0: no compatible PCI ICU found: ICU vendor 0x8086
> > product 0x2640
> > pcibios0: Warning, unable to fix up PCI interrupt routing
> > pcibios0: PCI bus #5 is the last bus
> >
> > ... which as far as I can read, is "harmless", but potentially causing
> > higher interrupt load?
> >
> > Any hints as to where I should look next would be great. I'm about to
> > install the latest -current snapshot on the machine to see if
> > there's a
> > recent fix.
> >
> > I'm about 95% sure this is the motherboard we're using:
> > http://www.supermicro.com/products/motherboard/P4/E7221/P8SCT.
> > cfm I'll check
> > with the order guy and confirm the PO.
> >
> > There's a 3.4ghz P4 CPU in it, the two built-in nics, and a
> > single PCI-X
> > 133mhz PCI port which I used for the dual port server nic
> > from intel. SATA
> > harddrive for what it's worth. Running OpenBSD 3.7 as a PF
> > firewall. I've
> > tried changing a bunch of BIOS options, disabling interrupts,
> > etc. I haven't
> > compiled my own kernel or built the OS or anything.
> >
> > Thanks,
> > -Dormando
>
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