Super slow when running sshd

[Justin J]

Hi all,

I'm using dynamoRio inside a fedora container (`fedora 38`). The usage is super simple: `drrun /usr/sbin/sshd -D -e`, i.e., just start an SSH server. However the startup is super slow. Further more, the started server cannot handle any ssh connection becuase it's too slow and cause connection timeout.

As far as I understand, dynamoRio should not cause so much overhead. I digged a bit into the problem but cannot find any useful information. Thank you so much if you can give me any suggestions what may cause the overhead!

Best regards,

Justin

[Kai Luk]

Hi Justin,

Have you tried to increase the connection timeout, ConnectTimeout, of the ssh connection?

Are there specific areas or functions you are trying to trace?

There are ways to trace lower the overhead:

https://dynamorio.org/sec_drcachesim_partial.html

Regards,

Kai

[Justin J]

Hi Kai,

Thanks a lot for your reply! I'm not using any  Dynamorio clients. I simply run an SSH server using the `drrun` command. It looks like this is not the application's issue. I feel it's more related to the container env. Because when I run the same command in the host, it's pretty fast; but if running inside a container, it's very slow.