Ticket #1811 (closed defect: worksforme)

Opened 10 years ago

Last modified 10 years ago

Painfully slow direct I/O on Linux guest

Reported by: decoder Owned by:
Priority: major Component: other
Version: VirtualBox 1.6.2 Keywords: linux direct io performance
Cc: decoder@… Guest type: other
Host type: other



after experiencing quite slow I/O in general (Linux/Linux, compact vdi image), I did some experiments. In detail I created a file in the guest that I tried to overwrite with dd using direct I/O (dd if=/dev/zero of=/some.file bs=4M count=1000 conv=notrunc oflag=direct).

This command resulted in a writing speed of ~300 kb/s (yes, kb). The same thing in KVM resulted in a normal writing speed (30-50 mb/s) on a comparable host (although the second one has a slightly faster hdd setup, the hosts aren't the bottlenecks in this case).

Is this a known problem/expected behavior?

I am using Virtual Box 1.6.2 (closed) with the SATA controller.

I posted some more stats here: if this is relevant.

If you need further details, feel free to contact me.

Change History

comment:1 Changed 10 years ago by decoder

-_- please close as invalid, additions were not properly loaded, direct i/o is now working (and much faster than normal i/o even ...)

comment:2 Changed 10 years ago by frank

  • Status changed from new to closed
  • Resolution set to worksforme
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