Date: Sun, 6 Oct 2002 16:35:57 +0300 From: "Ido Barnea" <ido@cwnt.com> To: "Steve Francis" <steve@expertcity.com>, <freebsd-net@freebsd.org> Subject: RE: Help with net.inet.ip.intr_queue_maxlen Message-ID: <C7DF4400240AFB4095D98C7C6EC2A34A08336F@bart.cwnt.com>
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> -----Original Message----- > From: Steve Francis [mailto:steve@expertcity.com] > Sent: Sunday, October 06, 2002 3:13 AM > To: freebsd-net@freebsd.org > Subject: Help with net.inet.ip.intr_queue_maxlen > > > Can someone help me with net.inet.ip.intr_queue_maxlen tuning? > > Firstly, its the "size of the IP input queue", per the source. > > So does that mean after the NIC has received the packet, the interupt > from the NIC has been processed and the packet retrieved from the NIC, > then the packet is placed in this queue, before the IP stack > looks at it? > i.e. its unrelated to interupt coalescing or polling, or NIC > performance, as they have already occurred in order to put the packet > into the queue. Yes? > Absolutely correct > I am getting incrementing net.inet.ip.intr_queue_drops at around 8,000 > pps (increasing drops at rate of 10 or so per second.) > Yet, if my statement above about what the queue is, is > correct, then it > just means that the system was busy doing stuff before it had a chance > to process the incoming packets, so there was no room for new ones to > enter the queue. But as the system was only 50% busy, then if > I increase > the input queue, I should be able to avoid these drops, correct? At > least until the system gets a lot busier. > Correct again > Is there a sane upper recommended limit to the queue length? > Basically there shouldn't be a problem incrementing the queue length, since the space is not allocated in advance. So, you should experiment with few values until the drop rate drops to a reasonable value. The only problem I can think of is that you (or an attacker) can exhaust your mbuf pool if you allow the queue length to become too large. You can check out the state of your mbuf poll using 'netstat -m' > Or am I way off base here? > Thanks > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-net" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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