From mboxrd@z Thu Jan  1 00:00:00 1970
From: bugzilla-daemon@bugzilla.kernel.org
Subject: [Bug 42755] New: KVM is being extremely slow on AMD Athlon64 4000+
 Dual Core 2.1GHz Brisbane
Date: Fri, 10 Feb 2012 08:03:43 GMT
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https://bugzilla.kernel.org/show_bug.cgi?id=3D42755

           Summary: KVM is being extremely slow on AMD Athlon64 4000+ D=
ual
                    Core 2.1GHz Brisbane
           Product: Virtualization
           Version: unspecified
    Kernel Version: 3.2.2
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: kvm
        AssignedTo: virtualization_kvm@kernel-bugs.osdl.org
        ReportedBy: sandikata@yandex.ru
        Regression: No


Hello.

Kvm seems to be broken on AMD Athlon64 4000+ Dual Core 2.1GHz Brisbane.=
 A
kernel build takes over
2 hours, compared to 15 minutes on the host. I'm running with virtio
for storage, and this does not seem to be related to IO. A simple test
with dd also demonstrates that the problem is cpu-ralated:

Host test:
dd if=3D/dev/zero of=3D/dev/null bs=3D1k count=3D8M
8388608+0 =D0=B7=D0=B0=D0=BF=D0=B8=D1=81=D0=B5=D0=B9 =D1=81=D1=87=D0=B8=
=D1=82=D0=B0=D0=BD=D0=BE (read)
8388608+0 =D0=B7=D0=B0=D0=BF=D0=B8=D1=81=D0=B5=D0=B9 =D0=BD=D0=B0=D0=BF=
=D0=B8=D1=81=D0=B0=D0=BD=D0=BE (write)
 =D1=81=D0=BA=D0=BE=D0=BF=D0=B8=D1=80=D0=BE=D0=B2=D0=B0=D0=BD=D0=BE (co=
pyed) 8589934592 =D0=B1=D0=B0=D0=B9=D1=82=D0=B0 (8,6 GB), 7,04456 c, 1,=
2 GB/c

This also does not seem to be a cpu bug, as both VirtualBox and VMware
work fine.

Vmware/Virtualbox test:
dd if=3D/dev/zero of=3D/dev/null bs=3D1k count=3D8M
8388608+0 =D0=B7=D0=B0=D0=BF=D0=B8=D1=81=D0=B5=D0=B9 =D1=81=D1=87=D0=B8=
=D1=82=D0=B0=D0=BD=D0=BE (read)
8388608+0 =D0=B7=D0=B0=D0=BF=D0=B8=D1=81=D0=B5=D0=B9 =D0=BD=D0=B0=D0=BF=
=D0=B8=D1=81=D0=B0=D0=BD=D0=BE (write)
 =D1=81=D0=BA=D0=BE=D0=BF=D0=B8=D1=80=D0=BE=D0=B2=D0=B0=D0=BD=D0=BE (co=
pyed) 8589934592 =D0=B1=D0=B0=D0=B9=D1=82=D0=B0 (8,6 GB), 5,02745 c, 1,=
7 GB/c

I've tried different kernels on host, between 2.6.22 and current git,
with the same results. The guest is running Gentoo Hardened kernel 3.2.=
2
, but I could try with a an other distro and a vanilla kernel
if required.

My kvm version is kvm 1.0

Help would be much appreciated.

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