Hi Cole,
thanks for the hint on that fix.
I have applied and tried it but it still uses falloc for the allocation calls
from virt-manager.
I have traced a -O0 build in libvirt and see this:
Thread 6 "rpc-worker" hit Breakpoint 4, storageBackendCreateQemuImgOpts
(encinfo=0x0, opts=0x7fd1791102a0, info=0x7fd179110380) at
../../../src/storage/storage_util.c:712
(gdb) p *info
$3 = {format = 14, type = 0x7fd17ef920f0 "qcow2", inputType = 0x0, path =
0x7fd164018440 "/var/lib/libvirt/images/ubuntu20.04-l.qcow2", size_arg =
2097152, allocation = 2097152,
encryption = false, preallocate = true, compat = 0x7fd16400deb0 "1.1",
features = 0x7fd16400e170, nocow = false, backingPath = 0x0, backingFormat = 0,
inputPath = 0x0,
inputFormatStr = 0x0, inputFormat = 0, secretAlias = 0x0}
And in particular:
(gdb) p info->preallocate
$4 = true
(gdb) p info->size_arg
$5 = 2097152
(gdb) p info->allocation
$6 = 2097152
Due to that the following
712 if (info->preallocate) {
713 if (info->size_arg > info->allocation)
714 virBufferAddLit(&buf, "preallocation=metadata,");
715 else
716 virBufferAddLit(&buf, "preallocation=falloc,");
Still decides for falloc as the values are now (due to the fix) equal
but not greater than.
Per the description of the initial patch: "build them with
preallocation=falloc whenever the XML described storage <allocation>
matches its <capacity>" I wonder if we should change the libvirt code to
something like:
if (info.preallocate) {
if (info.size_arg == info.allocation)
virBufferAddLit(&buf, "preallocation=falloc,");
else
virBufferAddLit(&buf, "preallocation=metadata,");
}
That code would then work and read exactly as the description did.
P.S. reopening the case
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https://bugs.launchpad.net/bugs/1847105
Title:
very slow disk creation, snapshotting
Status in virt-manager:
Confirmed
Status in Native ZFS for Linux:
New
Status in libvirt package in Ubuntu:
Triaged
Status in virt-manager package in Ubuntu:
Triaged
Status in zfs-linux package in Ubuntu:
New
Status in libvirt source package in Bionic:
Invalid
Status in virt-manager source package in Bionic:
Invalid
Status in zfs-linux source package in Bionic:
Won't Fix
Status in libvirt source package in Disco:
Won't Fix
Status in virt-manager source package in Disco:
Won't Fix
Status in zfs-linux source package in Disco:
Won't Fix
Status in libvirt source package in Focal:
Triaged
Status in libvirt source package in Groovy:
Triaged
Bug description:
This is a regression in eoan for me. I use virt-manager to create vms,
and I noticed that creating one now takes more than a minute.
Looking at the process listing while the backing disk is being created, I see
this qemu-img command line:
15658 ? Ssl 0:00 /usr/sbin/libvirtd
23726 ? Sl 0:04 \_ /usr/bin/qemu-img create -f qcow2 -o
preallocation=falloc,compat=1.1,lazy_refcounts
/var/lib/libvirt/images/live-server.qcow2 41943040K
If I run qemu-img with that preallocation parameter set, even on
bionic, then it also takes a very long time.
On eoan, for comparison:
andreas@nsn7:~$ time qemu-img create -f qcow2 no-prealloc-image.qcow2 40G
Formatting 'no-prealloc-image.qcow2', fmt=qcow2 size=42949672960
cluster_size=65536 lazy_refcounts=off refcount_bits=16
real 0m0,016s
user 0m0,010s
sys 0m0,006s
andreas@nsn7:~$ qemu-img info no-prealloc-image.qcow2
image: no-prealloc-image.qcow2
file format: qcow2
virtual size: 40G (42949672960 bytes)
disk size: 17K
cluster_size: 65536
Format specific information:
compat: 1.1
lazy refcounts: false
refcount bits: 16
corrupt: false
andreas@nsn7:~$ du -hs no-prealloc-image.qcow2
17K no-prealloc-image.qcow2
andreas@nsn7:~$
and now with preallocation=falloc:
andreas@nsn7:~$ time qemu-img create -f qcow2 -o preallocation=falloc
with-prealloc-image.qcow2 40G
Formatting 'with-prealloc-image.qcow2', fmt=qcow2 size=42949672960
cluster_size=65536 preallocation=falloc lazy_refcounts=off refcount_bits=16
real 1m43,196s
user 0m3,564s
sys 1m26,720s
andreas@nsn7:~$ qemu-img info with-prealloc-image.qcow2
image: with-prealloc-image.qcow2
file format: qcow2
virtual size: 40G (42949672960 bytes)
disk size: 2.7M
cluster_size: 65536
Format specific information:
compat: 1.1
lazy refcounts: false
refcount bits: 16
corrupt: false
andreas@nsn7:~$ du -hs with-prealloc-image.qcow2
2,8M with-prealloc-image.qcow2
andreas@nsn7:~$
ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: libvirt-daemon 5.4.0-0ubuntu5
ProcVersionSignature: Ubuntu 5.3.0-13.14-generic 5.3.0
Uname: Linux 5.3.0-13-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu7
Architecture: amd64
Date: Mon Oct 7 11:36:03 2019
InstallationDate: Installed on 2019-10-07 (0 days ago)
InstallationMedia: Ubuntu 19.10 "Eoan Ermine" - Beta amd64 (20191006)
SourcePackage: libvirt
UpgradeStatus: No upgrade log present (probably fresh install)
modified.conffile..etc.libvirt.nwfilter.allow-arp.xml: [inaccessible: [Errno
13] Permission denied: '/etc/libvirt/nwfilter/allow-arp.xml']
modified.conffile..etc.libvirt.nwfilter.allow-dhcp-server.xml: [inaccessible:
[Errno 13] Permission denied: '/etc/libvirt/nwfilter/allow-dhcp-server.xml']
modified.conffile..etc.libvirt.nwfilter.allow-dhcp.xml: [inaccessible: [Errno
13] Permission denied: '/etc/libvirt/nwfilter/allow-dhcp.xml']
modified.conffile..etc.libvirt.nwfilter.allow-incoming-ipv4.xml:
[inaccessible: [Errno 13] Permission denied:
'/etc/libvirt/nwfilter/allow-incoming-ipv4.xml']
modified.conffile..etc.libvirt.nwfilter.allow-ipv4.xml: [inaccessible: [Errno
13] Permission denied: '/etc/libvirt/nwfilter/allow-ipv4.xml']
modified.conffile..etc.libvirt.nwfilter.clean-traffic-gateway.xml:
[inaccessible: [Errno 13] Permission denied:
'/etc/libvirt/nwfilter/clean-traffic-gateway.xml']
modified.conffile..etc.libvirt.nwfilter.clean-traffic.xml: [inaccessible:
[Errno 13] Permission denied: '/etc/libvirt/nwfilter/clean-traffic.xml']
modified.conffile..etc.libvirt.nwfilter.no-arp-ip-spoofing.xml:
[inaccessible: [Errno 13] Permission denied:
'/etc/libvirt/nwfilter/no-arp-ip-spoofing.xml']
modified.conffile..etc.libvirt.nwfilter.no-arp-mac-spoofing.xml:
[inaccessible: [Errno 13] Permission denied:
'/etc/libvirt/nwfilter/no-arp-mac-spoofing.xml']
modified.conffile..etc.libvirt.nwfilter.no-arp-spoofing.xml: [inaccessible:
[Errno 13] Permission denied: '/etc/libvirt/nwfilter/no-arp-spoofing.xml']
modified.conffile..etc.libvirt.nwfilter.no-ip-multicast.xml: [inaccessible:
[Errno 13] Permission denied: '/etc/libvirt/nwfilter/no-ip-multicast.xml']
modified.conffile..etc.libvirt.nwfilter.no-ip-spoofing.xml: [inaccessible:
[Errno 13] Permission denied: '/etc/libvirt/nwfilter/no-ip-spoofing.xml']
modified.conffile..etc.libvirt.nwfilter.no-mac-broadcast.xml: [inaccessible:
[Errno 13] Permission denied: '/etc/libvirt/nwfilter/no-mac-broadcast.xml']
modified.conffile..etc.libvirt.nwfilter.no-mac-spoofing.xml: [inaccessible:
[Errno 13] Permission denied: '/etc/libvirt/nwfilter/no-mac-spoofing.xml']
modified.conffile..etc.libvirt.nwfilter.no-other-l2-traffic.xml:
[inaccessible: [Errno 13] Permission denied:
'/etc/libvirt/nwfilter/no-other-l2-traffic.xml']
modified.conffile..etc.libvirt.nwfilter.no-other-rarp-traffic.xml:
[inaccessible: [Errno 13] Permission denied:
'/etc/libvirt/nwfilter/no-other-rarp-traffic.xml']
modified.conffile..etc.libvirt.nwfilter.qemu-announce-self-rarp.xml:
[inaccessible: [Errno 13] Permission denied:
'/etc/libvirt/nwfilter/qemu-announce-self-rarp.xml']
modified.conffile..etc.libvirt.nwfilter.qemu-announce-self.xml:
[inaccessible: [Errno 13] Permission denied:
'/etc/libvirt/nwfilter/qemu-announce-self.xml']
modified.conffile..etc.libvirt.qemu.conf: [inaccessible: [Errno 13]
Permission denied: '/etc/libvirt/qemu.conf']
modified.conffile..etc.libvirt.qemu.networks.default.xml: [inaccessible:
[Errno 13] Permission denied: '/etc/libvirt/qemu/networks/default.xml']
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