freebsd router project. Problems with polling?

Gleb Smirnoff glebius at
Sat Jan 29 08:30:10 PST 2005


  can you try if_em driver from HEAD and check whether this help.
There were some work done during 5.3-RELEASE.

On Fri, Jan 28, 2005 at 06:18:19PM +0100, Thomas Vogt wrote:
T> netstat -w 1 (polling disabled) 
T>             input        (Total)           output
T>    packets  errs      bytes    packets  errs      bytes colls
T>     300531     0   23441438     300585     0   23444792     0
T>     300939     0   25872898     300895     0   25870184     0
T>     300738     0   23457584     300768     0   23460626     0
T>     300304    10   25826466     300304     0   25826876     0
T>     ...
T> Interrupt load is about 70% with net.inet.ip.fastforwarding enabled. If
T> I disable this the system becomes unusable. 
T> The system hasn't reach the limit yet. But the interrupt is much to
T> high. It's not worthy to add a second udp sender machine, at the moment.
T> netstat -w 1 (polling enabled)
T>             input        (Total)           output
T>    packets  errs      bytes    packets  errs      bytes colls
T>     150151 47647   12910330     150150     0   12911806     0
T>     150151     0   11711798     150152     0   11711876     0
T>     150151 47665   12910986     150151     0   12911810     0
T>     150151     0   11711798     150151     0   11711798     0
T>     ...
T> Interrupt load is about 10%. CPU is about 60% and with
T> kern.polling.idle_poll enabled it goes to 100% (as expected). 
T> As you see the speed is droping down to 50% with polling enable and and
T> I got a lot of errors. 
T> kern.polling.lost_polls: 188748 and kern.polling.suspect: 186919 are
T> also very high. I don't know why polling is so bad on this machine. All
T> SMP option are disabled in the kernel and bios. 
T> I tried to do as much as in
T> described.
T> I will prepare others tests with -STABLE and -CURRENT in the next few
T> days. At the mean time, are they some other magic things config option I
T> can try? Perhaps increase the HZ to 2000 in the kernel or remove polling
T> and try smp machine? I doubt that I can run the machine without polling.
T> If you see 70% interrupt load with 300k pps without polling.
T> regards
T> Thomas Vogt
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Totus tuus, Glebius.

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