Running tcpdump in a VM improves performance of scp transfers
Issue
- When tcpdump is running in a KVM VM and then a transfer with scp is performed the performance is double that found when tcpdump is not running.
- Does not matter if tcpdump is run with promiscuous mode on or off (-p).
- Turning on promiscuous mode but not running tcpdump does not increase performance.
- Only affects scp. Transfers with dd and netcat are always just as fast as the performance found when running scp with tcpdump.
Environment
- Red Hat Enterprise Linux 5
- KVM
- tcpdump
- scp
- HP ProLiant DL580 G7
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