[pve-devel] [PATCH] Add patches for iothread_vq
DERUMIER, Alexandre
alexandre.derumier at groupe-cyllene.com
Fri Jun 27 09:01:46 CEST 2025
Hi Dominik,
I'm going to send patch to use json format by default for -device
options, It should help here
I have a patch for multiple iothreads too on my side (for both virtio
&& virtio-scsi), maybe we could compare implementation.
on my side, I'm using use same implementation than libvirt,
iothreads: x , are defined globally, and shared accross all disk by
default. (redhat said that it's better to not have too much threads, or
not busy thread, so shared iothreads are better by default).
optionally, user is able to define specific iothreads list by disk
some notes:
iothreads need to be < host cores. (I thinked it was vm cores but
finally the iothreads are unrelated to vm vcpu)
Redhat doc said that it's not playing fine with cache=writeback &&
aio=threads (not sure about aio=io_uring). So this need to be tested,
but maybe it need to fallback to 1thread is this case.
Also, your implementation is missing hotplug
-------- Message initial --------
De: Dominik Budzowski <dbudzowski at alfaline.pl>
Répondre à: Proxmox VE development discussion <pve-
devel at lists.proxmox.com>
À: pve-devel at lists.proxmox.com
Objet: [pve-devel] [PATCH] Add patches for iothread_vq
Date: 26/06/2025 00:15:35
---
drive-iothread-vq-pve8.4.patch | 33 ++++++++
qemuserver-iothread-vq-pve8.4.patch | 123 ++++++++++++++++++++++++++++
2 files changed, 156 insertions(+)
create mode 100644 drive-iothread-vq-pve8.4.patch
create mode 100644 qemuserver-iothread-vq-pve8.4.patch
diff --git a/drive-iothread-vq-pve8.4.patch b/drive-iothread-vq-
pve8.4.patch
new file mode 100644
index 0000000..0fd39be
--- /dev/null
+++ b/drive-iothread-vq-pve8.4.patch
@@ -0,0 +1,33 @@
+--- Drive.pm 2025-06-09 18:31:45.482659331 +0200
++++ Drive.pm 2025-06-09 19:00:29.962125989 +0200
+@@ -275,6 +275,14 @@
+ optional => 1,
+ });
+
++my %iothread_vq_mapping_fmt = ( iothread_vq_mapping => {
++ type => 'integer',
++ description => "Whether to use iothread-vq-mapping for this
drive",
++ minimum => 2,
++ maximum => 16,
++ optional => 1,
++});
++
+ my %product_fmt = (
+ product => {
+ type => 'string',
+@@ -442,6 +450,7 @@
+ my $virtio_fmt = {
+ %drivedesc_base,
+ %iothread_fmt,
++ %iothread_vq_mapping_fmt,
+ %readonly_fmt,
+ };
+ my $virtiodesc = {
+@@ -537,6 +546,7 @@
+ my $alldrive_fmt = {
+ %drivedesc_base,
+ %iothread_fmt,
++ %iothread_vq_mapping_fmt,
+ %model_fmt,
+ %product_fmt,
+ %queues_fmt,
diff --git a/qemuserver-iothread-vq-pve8.4.patch b/qemuserver-iothread-
vq-pve8.4.patch
new file mode 100644
index 0000000..9719091
--- /dev/null
+++ b/qemuserver-iothread-vq-pve8.4.patch
@@ -0,0 +1,123 @@
+--- QemuServer.pm 2025-06-25 22:36:12.414594136 +0200
++++ QemuServer.pm 2025-06-25 23:22:38.522270102 +0200
+@@ -1301,17 +1301,79 @@
+ return "usb-kbd,id=keyboard,bus=ehci.0,port=2";
+ }
+
++# Helper to generate iothread/VQ mapping for block devices
++sub generate_iothread_vq_mapping {
++ my ($vmid, $drive) = @_;
++ my ($use_iothread_vq_mapping, $use_iothread, @vq_map);
++
++ if ($drive->{iothread_vq_mapping}) {
++ $use_iothread_vq_mapping = 1;
++ @vq_map = map { { iothread => "iothread-${vmid}-$_" } }
++ 0 .. $drive->{iothread_vq_mapping} - 1;
++ } elsif ($drive->{iothread}) {
++ $use_iothread = 1;
++ }
++
++ return ($use_iothread_vq_mapping, $use_iothread, \@vq_map);
++}
++
++# Main sub: JSON encoder for ordered key-value pairs and full drive
device construction
+ sub print_drivedevice_full {
+ my ($storecfg, $conf, $vmid, $drive, $bridges, $arch,
$machine_type) = @_;
+
+- my $device = '';
+- my $maxdev = 0;
+-
++ # Compute drive ID and PCI address for virtio
+ my $drive_id = PVE::QemuServer::Drive::get_drive_id($drive);
++ my $pciaddr = '';
++ if ($drive->{interface} eq 'virtio') {
++ $pciaddr = print_pci_addr($drive_id, $bridges, $arch,
$machine_type);
++ }
++
++ # Generate iothread/VQ mapping flags and mapping array
++ my ($use_iothread_vq_mapping, $use_iothread, $vq_map_ref) =
++ generate_iothread_vq_mapping($vmid, $drive);
++
++ # Prepare base JSON encoder
++ my $json = JSON->new->canonical(1);
++ my $device;
++
++ # Virtio interface handling
+ if ($drive->{interface} eq 'virtio') {
+- my $pciaddr = print_pci_addr("$drive_id", $bridges, $arch,
$machine_type);
+- $device = "virtio-blk-pci,drive=drive-
$drive_id,id=${drive_id}${pciaddr}";
+- $device .= ",iothread=iothread-$drive_id" if $drive-
>{iothread};
++ if ($use_iothread_vq_mapping) {
++ my ($bus, $addr) = ();
++ if ($pciaddr =~ /^,bus=([^,]+),addr=(.+)$/) {
++ ($bus, $addr) = ($1, $2);
++ }
++ my @fields = (
++ [ driver => 'virtio-blk-pci' ],
++ [ 'iothread-vq-mapping' => $vq_map_ref ],
++ [ 'queue-size' => 1024 ],
++ [ 'config-wce' => JSON::false ],
++ [ drive => "drive-$drive_id" ],
++ [ id => $drive_id ],
++ [ bus => $bus ],
++ [ addr => $addr ],
++ ($drive->{bootindex} ? [ bootindex => $drive-
>{bootindex} ] : ()),
++ );
++ my @parts;
++ for my $fld (@fields) {
++ my ($k, $v) = @$fld;
++ push @parts, $json->encode($k) . ':' . $json-
>encode($v);
++ }
++ $device = '{' . join(',', @parts) . '}';
++ }
++ elsif ($use_iothread) {
++ $device = sprintf(
++ 'virtio-blk-pci,drive=drive-
%s,id=%s%s,iothread=iothread-%s',
++ $drive_id, $drive_id, $pciaddr, $drive_id
++ );
++ }
++ else {
++ $device = sprintf(
++ 'virtio-blk-pci,drive=drive-%s,id=%s%s',
++ $drive_id, $drive_id, $pciaddr
++ );
++ }
++
+ } elsif ($drive->{interface} eq 'scsi') {
+
+ my ($maxdev, $controller, $controller_prefix) =
scsihw_infos($conf, $drive);
+@@ -1386,7 +1448,7 @@
+ die "unsupported interface type";
+ }
+
+- $device .= ",bootindex=$drive->{bootindex}" if $drive-
>{bootindex};
++ $device .= ",bootindex=$drive->{bootindex}" if $drive-
>{bootindex} && !$use_iothread_vq_mapping;
+
+ if (my $serial = $drive->{serial}) {
+ $serial = URI::Escape::uri_unescape($serial);
+@@ -3911,8 +3973,23 @@
+
+ $drive->{bootindex} = $bootorder->{$ds} if $bootorder->{$ds};
+
+- if ($drive->{interface} eq 'virtio'){
+- push @$cmd, '-object', "iothread,id=iothread-$ds" if
$drive->{iothread};
++# if ($drive->{interface} eq 'virtio'){
++# push @$cmd, '-object', "iothread,id=iothread-$ds" if
$drive->{iothread};
++# }
++
++ if ($drive->{interface} eq 'virtio') {
++
++ if ($drive->{iothread_vq_mapping}) {
++
++ for my $i (0 .. $drive->{iothread_vq_mapping} - 1) {
++ my $id = "iothread,id=iothread-$vmid-$i";
++ push @$cmd, ('-object', $id) unless grep { $_ eq
$id } @$cmd;
++ }
++ } elsif ($drive->{iothread}) {
++
++ my $id = "iothread,id=iothread-$ds";
++ push @$cmd, ('-object', $id) unless grep { $_ eq $id }
@$cmd;
++ }
+ }
+
+ if ($drive->{interface} eq 'scsi') {
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