Bug 250516 - Poor performance if running as guest OS on QEMU
Summary: Poor performance if running as guest OS on QEMU
Status: New
Alias: None
Product: Base System
Classification: Unclassified
Component: misc (show other bugs)
Version: 12.1-RELEASE
Hardware: Any Any
: --- Affects Some People
Assignee: freebsd-virtualization (Nobody)
Depends on:
Reported: 2020-10-22 01:46 UTC by Charlie
Modified: 2021-11-24 15:41 UTC (History)
3 users (show)

See Also:


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Description Charlie 2020-10-22 01:46:06 UTC

I am new here and trying to find answers to the issue described below.

We make PCI chip which mainly plugged in Linux systems.
If I installed FreeBSD 12.1 on actual HW (i.e. x86), PCI throughput is fine and compatible with other Linux OSes like Ubuntu or CentOS.

But, if I run it as a guest OS on QEMU, then the PCI throughput is very very low. This is compared to the same tests I run on Ubuntu or CentOS as guest OS on the same QEMU.

So, I would like to know:
1. Do you have any report about the same situation: PCI throughput is very low if FreeBSD runs as guest OS on QEMU?
2. What kind of data you need me to capture in order for you to debug further?

Please let me know.

Comment 1 Mark Linimon freebsd_committer freebsd_triage 2021-06-30 00:14:15 UTC
^Triage: reassign.  I'm sorry that this did not get done sooner.
Comment 2 rainer 2021-06-30 07:01:36 UTC

I have the same problem, running FreeBSD as a guest in Openstack (which uses kvm/qemu).

I actually had the same problem running it under Xen. So it's been going like that for at least five years.

See here:

Comment 3 Frank Wall 2021-11-24 15:41:39 UTC
I don't have this issue when using FreeBSD 13.0 on oVirt (also based on KVM/qemu). So I'm wondering how you measure and compare the performance between FreeBSD and Linux.