[Pkg-libvirt-maintainers] Bug#843878: libvirt-daemon: Can't query numad(8) for auto NUMA vCPU Pinning ("numad is not available on this host")

Guilhem Moulin guilhem at guilhem.org
Thu Nov 10 11:58:34 UTC 2016


Package: libvirt-daemon
Version: 2.4.0-1+b1
Severity: normal
Tags: patch

Dear Maintainer,

Pinning domain processes and vCPUs to physical CPUs increases cache
efficiency [0].  One can add a ‘cpuset’ attribute to the <vcpu> element
to explicitely list physical CPU numbers [1]; however I find it more
flexible to specify a placement *mode* instead, and let libvirtd query
numad(8) to find the best alignment for the guest's CPUs and memory
resources.

Unfortunately adding the following snippet yields "numad is not
available on this host" and the domain refuses to start.

    <vcpu placement='auto'>2</vcpu>
    <numatune>
        <memory mode='preferred' placement='auto'/>
    </numatune>

It turns out that while libvirtd is compiled with --with-numactl, it's
missing --with-numad.  The enclosed patch passes this flag, and adds
‘numad’ to Build-Depends and libvirt-daemon's Suggests.

I also had to regorganize the PATH in which to search for the numad
binary, probably because I use split-usr.  (Without the second patch,
the binary is hardcoded to /bin/numad while the numad package ships
/usr/bin/numad instead.)

Thanks for maintaining libvirt in Debian!
Cheers 
-- 
Guilhem.

[0] https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html-single/Virtualization_Tuning_and_Optimization_Guide/index.html#chap-Virtualization_Tuning_Optimization_Guide-NUMA
[1] https://libvirt.org/formatdomain.html#elementsCPUAllocation


-- System Information:
Debian Release: stretch/sid
  APT prefers unstable
  APT policy: (990, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 4.8.0-1-amd64 (SMP w/8 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages libvirt-daemon depends on:
ii  libapparmor1        2.10.95-6
ii  libaudit1           1:2.6.7-1
ii  libavahi-client3    0.6.32-1
ii  libavahi-common3    0.6.32-1
ii  libblkid1           2.29-1
ii  libc6               2.24-5
ii  libcap-ng0          0.7.7-3
ii  libdbus-1-3         1.10.12-1
ii  libdevmapper1.02.1  2:1.02.133-1
ii  libfuse2            2.9.7-1
ii  libgnutls30         3.5.5-6
ii  libnetcf1           1:0.2.8-1+b1
ii  libnl-3-200         3.2.27-1
ii  libnl-route-3-200   3.2.27-1
ii  libnuma1            2.0.11-2
ii  libparted2          3.2-16+b1
ii  libpcap0.8          1.8.1-3
ii  libpciaccess0       0.13.4-1
ii  librados2           0.80.11-1.1
ii  librbd1             0.80.11-1.1
ii  libsasl2-2          2.1.27~72-g88d82a3+dfsg-1
ii  libselinux1         2.6-3
ii  libssh2-1           1.7.0-1
ii  libudev1            232-2
ii  libvirt0            2.4.0-1+b1
ii  libxen-4.8          4.8.0~rc3-1
ii  libxenstore3.0      4.8.0~rc3-1
ii  libxml2             2.9.4+dfsg1-2.1
ii  libyajl2            2.1.0-2

Versions of packages libvirt-daemon recommends:
pn  libxml2-utils   <none>
ii  netcat-openbsd  1.105-7
ii  qemu-kvm        1:2.7+dfsg-3+b1

Versions of packages libvirt-daemon suggests:
ii  libvirt-daemon-system  2.4.0-1+b1

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