[Iftop-users] CPU use bug?

[Paul Warren]

Hi Alex,

I'm a bit short of ideas, but the fact that port display affects it 
makes me think that it's not directly hardware related, as port display 
makes no difference to how the packets are captured, it just makes a 
difference to how much work iftop does with them once received.

Does the traffic involve a large number of different hosts?  Do you have 
any screen filters turned on?  Does turning host resolution off make any 
difference?

Paul

On 12/11/2013 18:05, Alex Page wrote:
> Hi Paul,
>
> Not a ton of traffic, tens or hundreds of kbps... it doesn't seem to
> depend on this.  The highest typical amount would be 10-50Mbps, or
> occasionally up near 1Gbps on 1 of the faulty machines.  It definitely
> seems NIC/driver-dependent, though, as I tried a wifi dongle on one of
> the bad machines and the problem didn't present itself on that
> interface.  And as I mentioned, it has worked in the past on the same
> hardware.
>
> Alex
>
>
> On 11/12/2013 05:24 AM, Paul Warren wrote:
>> Hi Alex,
>>
>> Apologies for the delay in replying to this.
>>
>> How much traffic is being seen on the machines involved?
>>
>> Paul
>>
>> On 02/11/2013 12:05, Alex Page wrote:
>>> Hello,
>>> I am seeing strange behavior recently in iftop on Ubuntu (x64, 12.04 and
>>> 13.10).  With Port Display disabled, iftop simply uses more CPU than
>>> normal (say, 20% instead of a negligible amount).  Then, when Port
>>> Display is enabled, CPU use goes straight to 100% and iftop becomes
>>> unresponsive.
>>>
>>> This behavior started sometime in the last few months, and occurs on 2
>>> of the 4 Ubuntu machines that I've tested it on.  I compiled iftop 0.17
>>> and 1.0-pre2 from source and observed the same behavior as the
>>> precompiled version (1.0-pre2 from the Ubuntu repo) on these computers.
>>>
>>> I cannot figure out what is unique (other than physical hardware) about
>>> the 2 machines that still work, except that they use 3.2 and 3.6 kernels
>>> (vs. 3.5 and 3.11 on the machines that don't work).  So maybe there's a
>>> network driver issue?  I checked the version numbers of libc6,
>>> libncurses, libpcap, and libtinfo (all the dependencies I know of) and
>>> they are the same on 1 of the working machines vs. 1 of the non-working
>>> ones.  And iftop worked properly on all of these machines until some
>>> relatively recent update.
>>>
>>> So, iftop is completely unusable on at least 2 of my computers.  Can
>>> anyone recommend further troubleshooting steps that I could take to
>>> isolate this problem, preferably without rebooting?  Are there any other
>>> library versions I should check?
>>>
>>> Thanks,
>>> Alex
>>>
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>>>
>>
>>
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