summary refs log tree commit diff stats
path: root/gitlab/issues_text/target_missing/host_missing/accel_missing/1307
diff options
context:
space:
mode:
authorChristian Krinitsin <mail@krinitsin.com>2025-06-01 21:35:14 +0200
committerChristian Krinitsin <mail@krinitsin.com>2025-06-01 21:35:14 +0200
commit3e4c5a6261770bced301b5e74233e7866166ea5b (patch)
tree9379fddaba693ef8a045da06efee8529baa5f6f4 /gitlab/issues_text/target_missing/host_missing/accel_missing/1307
parente5634e2806195bee44407853c4bf8776f7abfa4f (diff)
downloadqemu-analysis-3e4c5a6261770bced301b5e74233e7866166ea5b.tar.gz
qemu-analysis-3e4c5a6261770bced301b5e74233e7866166ea5b.zip
clean up repository
Diffstat (limited to 'gitlab/issues_text/target_missing/host_missing/accel_missing/1307')
-rw-r--r--gitlab/issues_text/target_missing/host_missing/accel_missing/130772
1 files changed, 0 insertions, 72 deletions
diff --git a/gitlab/issues_text/target_missing/host_missing/accel_missing/1307 b/gitlab/issues_text/target_missing/host_missing/accel_missing/1307
deleted file mode 100644
index 9e90d8ad4..000000000
--- a/gitlab/issues_text/target_missing/host_missing/accel_missing/1307
+++ /dev/null
@@ -1,72 +0,0 @@
-query-named-block-nodes, without flat=true, is massively slow as number of block nodes increases
-Description of problem:
-The query-named-block-nodes command is insanely slow with deep backing chains when the flat=true arg is NOT given.
-
-```
-qemu-img create demo0.qcow2 1g
-j=0
-for i in `seq 1 199`
-do 
-    qemu-img create -f qcow2 -o backing_file=demo$j.qcow2 -o backing_fmt=qcow2 demo$i.qcow2
-    j=$i
-done
-```
-
-Now configure libvirt with
-
-```
-    <disk type='file' device='disk'>
-      <driver name='qemu' type='qcow2' discard='unmap'/>
-      <source file='/var/lib/libvirt/images/demo199.qcow2'/>
-      <target dev='vdb' bus='virtio'/>
-      <address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/>
-    </disk>
-```
-
-This results in `-blockdev` args
-
-```
--blockdev '{"driver":"file","filename":"/var/lib/libvirt/images/demo0.qcow2","node-name":"libvirt-201-storage","auto-read-only":true,"discard":"unmap"}' \
--blockdev '{"node-name":"libvirt-201-format","read-only":true,"discard":"unmap","driver":"qcow2","file":"libvirt-201-storage","backing":null}' \
--blockdev '{"driver":"file","filename":"/var/lib/libvirt/images/demo1.qcow2","node-name":"libvirt-200-storage","auto-read-only":true,"discard":"unmap"}' \
--blockdev '{"node-name":"libvirt-200-format","read-only":true,"discard":"unmap","driver":"qcow2","file":"libvirt-200-storage","backing":"libvirt-201-format"}' \
--blockdev '{"driver":"file","filename":"/var/lib/libvirt/images/demo2.qcow2","node-name":"libvirt-199-storage","auto-read-only":true,"discard":"unmap"}' \
--blockdev '{"node-name":"libvirt-199-format","read-only":true,"discard":"unmap","driver":"qcow2","file":"libvirt-199-storage","backing":"libvirt-200-format"}' \
-...snip...
--blockdev '{"driver":"file","filename":"/var/lib/libvirt/images/demo197.qcow2","node-name":"libvirt-4-storage","auto-read-only":true,"discard":"unmap"}' \
--blockdev '{"node-name":"libvirt-4-format","read-only":true,"discard":"unmap","driver":"qcow2","file":"libvirt-4-storage","backing":"libvirt-5-format"}' \
--blockdev '{"driver":"file","filename":"/var/lib/libvirt/images/demo198.qcow2","node-name":"libvirt-3-storage","auto-read-only":true,"discard":"unmap"}' \
--blockdev '{"node-name":"libvirt-3-format","read-only":true,"discard":"unmap","driver":"qcow2","file":"libvirt-3-storage","backing":"libvirt-4-format"}' \
--blockdev '{"driver":"file","filename":"/var/lib/libvirt/images/demo199.qcow2","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}' \
--blockdev '{"node-name":"libvirt-1-format","read-only":false,"discard":"unmap","driver":"qcow2","file":"libvirt-1-storage","backing":"libvirt-3-format"}' \
--device '{"driver":"virtio-blk-pci","bus":"pci.7","addr":"0x0","drive":"libvirt-1-format","id":"virtio-disk1"}' \
-```
-
-Now stop libvirt
-
-```
-systemctl stop libvirtd
-```
-
-And speak directly to QMP
-
-```
-$ time socat UNIX:/var/lib/libvirt/qemu/domain-158-fedora38/monitor.sock - > /dev/null 
-{ "execute": "qmp_capabilities", "arguments": { "enable": ["oob"] } }
-{ "execute": "query-named-block-nodes"}
-{ "execute": "quit" }
-
-real	2m19.276s
-user	0m0.006s
-sys	0m0.014s
-```
-
-If we save the 'query-named-block-nodes' output instead of sending it to /dev/null, we get a 86 MB file for the QMP response. This will break all known client apps since they limit QMP reply size.
-
-It appears to have a combinatorial expansion of block nodes in the output.
-
-Blocking the main event loop for 2 minutes is obviously not good either.
-
-If we use '"flat": true' parameter to query-named-block-nodes, the command completes in just 15 seconds, and produces a large, but more manageable 2.7 MB
-
-Since the non-flat  query-named-block-nodes output is so incredibly non-scalable, I think we should deprecate non-flat mode, and eventually make  flat the mandatory option.