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During certain Achilles tests, CPU consumption of Samba rises to 100%.

I am doing Achilles tests on a Linux-based server. I have noticed that during certain tests (and UDP port discovery), the temperature of the CPU cores surges to around 80-90 °C which causes the CPU clock to throttle and renders the server practically unresponsive.

Following closer investigations, we found out that there is a direct link between the rise of CPU consumption by a certain process and the CPU temperature. In our case, the concerned process is Samba

We are using samba4 in the full active directory mode.

Environment details:

  • OS: Ubuntu 14.04 LTS
  • Samba version: 4.3.11

In our environment, there is a direct connection between the server running Samba and the test PC; no other element in the network.

As far as we understand, this looks like a DoS attack. Certain tests render the server completely unresponsive.

Is this a known issue? If yes, is there a fix for it?

Thank you in advance.

alexander.polomodov
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alibaba
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    If your server cooling cannot cool down the temperature during 100% usage I would rather check the cooling and if a fan failed. Trying to make a process responsible is the wrong end to fix things here. – Thomas Jul 02 '18 at 12:53
  • Well we have also contacted the server manufacturer regarding this issue. The purpose of my question was not to blame the process, in fact I would simply like to know why samba consumes 100% of my CPU under certain tests. It is definitely abnormal isn't it? – alibaba Jul 02 '18 at 15:43
  • If you stress test samba then it is very likely that it will reach 100% CPU usage. Under normal circumstances it is abnormal, but that also depends on the amount of samba mounts, what the users do, network traffic etc. – Thomas Jul 02 '18 at 15:48

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