Terrible ix performance

Steven Hartland killing at multiplay.co.uk
Thu Jul 4 08:16:03 UTC 2013

----- Original Message ----- 
>> On Wed, Jul 3, 2013 at 10:01 PM, Lawrence Stewart>> 
>>     On 07/04/13 10:18, Kevin Oberman wrote:
>>     > On Wed, Jul 3, 2013 at 4:21 PM, Steven Hartland
>>     >>
>>     >> Out of interest have you tried limiting the number of queues?
>>     >>
>>     >> If not give it a try see if it helps, add the following to
>>     >> /boot/loader.conf:
>>     >> hw.ixgbe.num_queues=1
>>     >>
>>     >> If nothing else will give you another data point.
>>     As noted in my first post to this thread, if iperf is able to push a
>>     single flow at 8Gbps, then the NIC is unlikely to be the source of the
>>     problem and trying to tune it is a waste of time (at least at this
>>     stage).
>>     iperf tests memory-network-memory transfer speed without any disk
>>     involvement, so the fact that it can get 8Gbps and ftp is getting around
>>     4Gbps implies that either the iperf TCP tuning is better (only likely to
>>     be relevant if the RTT is very large - Outback Dingo you still haven't
>>     provided us with the RTT) or the disk subsystem at one or both ends is
>>     slowing things down.

That may not be all the story, you'll have significantly different data
patterns between the two, so don't discount anything till you've tested.


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