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Thread: High sshd CPU usage during sftp transfers

  1. #1
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    Feb 2010
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    Question High sshd CPU usage during sftp transfers

    I'm running Xubuntu 12.04 x64 on an AMD 64 X2 4200 dual core 2.2GHz machine. I'm connecting to it via SFTP from my Windows machine over my 100mbps LAN, using FileZilla. I noticed that when I transfer large files, sshd consumes a lot of CPU time:


    • 1 transfer: Pegs one of my CPU cores at 100% and I only get around 80mbps transfer speed.
    • 2 transfers: Two sshd processes running at ~60% CPU usage each, and my transfer speed reaches the full 100mbps.
    • 3 transfers: Three sshd processes run at around ~45% CPU usage, and the transfer speeds seem to jitter whenever other processes need CPU time (I actually saw as low as 60mbps when I had something else CPU-intensive going on at the same time, which is what prompted me to post here).


    Are there any sshd/sftp settings I can tweak on the Xubuntu end to reduce CPU usage?

    I'm running an NFS server on the Windows machine, so I suppose I should probably just set up a mount to that on the Xubuntu machine and push the files across. I don't like using Samba because it seems to have transport overhead that often keeps it from getting close to 100% bandwidth utilization as well.

  2. #2
    Join Date
    Feb 2009
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    Ubuntu Gnome 14.04 Trusty Tahr

    Re: High sshd CPU usage during sftp transfers

    EDIT: Accidental double post.
    Last edited by lukeiamyourfather; September 14th, 2012 at 08:00 PM.

  3. #3
    Join Date
    Feb 2009
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    Ubuntu Gnome 14.04 Trusty Tahr

    Re: High sshd CPU usage during sftp transfers

    SFTP is encrypted using SSH (i.e. the sshd). Not using SFTP and just using FTP would improve performance. If simply mounting the share if you're on a local network is a much better option than SFTP.

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