Freebsd 10.3 network performance

Abdullah

New Member

Thanks: 1
Messages: 16

#1
I have a lanner 8759. With xeon e3-1275v3, 8gb ram and 8xIntel i210. I have bridges 2 of the 8 ports,
Initially with iperf i was getting around 940 mbps throughput. But on several occasions the test would start with somewhere around 500 and then stays almost same throughut iperf test. Other times when starting is 900+ it stays almost 900 plus.
THen i made some changes
hw.igb.rx_process_limit="-1"
hw.igb.num_queues="4"
Now i get throughput more than 900 on majority of occasions but even now some times i get that one odd instance of around 500 mbps. My question is what causes this?
vmstat -i shows that all the 4 queues for each interface are getting some interrupts, but not uniformly.
top shows interrupt %age on one core at about 4-5% with one other core about 1-2% occasionally. My understanding is taht having queues share load between separate cpu cores. Is that correct? Secondly is there any way to ensure that throughput stays 900+? And why does it drop so much in the first place without going any higher during the course of the test? But if i restart the test it goes right up over 900 instantly?
 
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