Date: Mon, 20 May 2013 16:02:08 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-net@freebsd.org Cc: "=?iso-8859-1?q?Cl=E9ment_Hermann?= \(nodens\)" <nodens2099@gmail.com> Subject: Re: High CPU interrupt load on intel I350T4 with igb on 8.3 Message-ID: <201305201602.08281.jhb@freebsd.org> In-Reply-To: <517A657B.7060003@gmail.com> References: <517A657B.7060003@gmail.com>
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On Friday, April 26, 2013 7:31:07 am Clément Hermann (nodens) wrote: > Hi list, > > We use pf+ALTQ for trafic shaping on some routers. > > We are switching to new servers : Dell PowerEdge R620 with 2 8-cores > Intel Processor (E5-2650L), 8GB RAM and Intel I350T4 (quad port) using > igb driver. The old hardware is using em driver, the CPU load is high > but mostly due to kernel and a large pf ruleset. > > On the new hardware, we see high CPU Interrupt load (up to 95%), even > though there is not much trafic currently (peaks about 150Mbps and > 40Kpps). All queues are used and binded to a cpu according to top, but a > lot of CPU time is spent on igb queues (interrupt or wait). The load is > fine when we stay below 20Kpps. > > We see no mbuf shortage, no dropped packet, but there is little margin > left on CPU time (about 25% idle at best, most of CPU time is spent on > interrupts), which is disturbing. > > We have done some tuning, but to no avail : If you have the processing_limit set to -1, you should never see CPU time spent in the igb task threads (any such time means there is a bug). One such bug was fixed in 8.x here (that is after 8.3): http://svnweb.freebsd.org/base?view=revision&revision=235553 This may not help with any issues in pf(4), but we had workloads at work (not involving pf) where this bug could cause boxes to spend 100% CPU in igb threads. -- John Baldwin
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