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>
next in thread | raw e-mail | index | archive | help
> -----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 >=20 >=20 > Can someone help me with net.inet.ip.intr_queue_maxlen tuning? >=20 > Firstly, its the "size of the IP input queue", per the source. >=20 > 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=20 > 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? >=20 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=20 > 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=20 > I increase > the input queue, I should be able to avoid these drops, correct? At > least until the system gets a lot busier. >=20 Correct again > Is there a sane upper recommended limit to the queue length? >=20 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 >=20 >=20 > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-net" in the body of the message >=20 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?C7DF4400240AFB4095D98C7C6EC2A34A08336F>