Re: [pve-devel] [PATCH v2 qemu-server 2/2] cfg2cmd: make io_uring default

[Stefan Reiter <s.reiter@proxmox.com>]

Note: This does not work when you have the 6.0 QEMU from the staging repo
installed, as it is built without io_uring - this patch is banking on us
only releasing a QEMU 6.0 to public with io_uring already baked in, i.e.
equating QEMU 6.0 with io_uring support enabled. Adding a +pve version or
similar for a version that'll probably never leave staging seemed
unnecessary.

For testing, build pve-qemu-kvm from git, as io_uring is already enabled
there.

On 6/21/21 5:33 PM, Stefan Reiter wrote:
> The 'aio' setting is not visible to the guest, and so can be changed
> during migrations or snapshots without issue. It is thus only
> dependendent on the actual QEMU version being >= 6.0, not machine
> version.
> 
> Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
> ---
> 
> new in v2
> 
> tested migration from and to old, both worked without issue
> 
>   PVE/QemuServer.pm                            | 22 +++++++++++++-------
>   test/cfg2cmd/pinned-version-pxe-pve.conf.cmd |  4 ++--
>   test/cfg2cmd/pinned-version-pxe.conf.cmd     |  4 ++--
>   test/cfg2cmd/pinned-version.conf.cmd         |  4 ++--
>   4 files changed, 21 insertions(+), 13 deletions(-)
> 
> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
> index fe31741..07dd14a 100644
> --- a/PVE/QemuServer.pm
> +++ b/PVE/QemuServer.pm
> @@ -1523,7 +1523,7 @@ sub get_initiator_name {
>   }
>   
>   sub print_drive_commandline_full {
> -    my ($storecfg, $vmid, $drive, $pbs_name) = @_;
> +    my ($storecfg, $vmid, $drive, $pbs_name, $io_uring) = @_;
>   
>       my $path;
>       my $volid = $drive->{file};
> @@ -1599,12 +1599,17 @@ sub print_drive_commandline_full {
>   	$cache_direct = 1;
>       }
>   
> -    # aio native works only with O_DIRECT
>       if (!$drive->{aio}) {
> -	if($cache_direct) {
> -	    $opts .= ",aio=native";
> +	if ($io_uring) {
> +	    # io_uring supports all cache modes
> +	    $opts .= ",aio=io_uring";
>   	} else {
> -	    $opts .= ",aio=threads";
> +	    # aio native works only with O_DIRECT
> +	    if($cache_direct) {
> +		$opts .= ",aio=native";
> +	    } else {
> +		$opts .= ",aio=threads";
> +	    }
>   	}
>       }
>   
> @@ -3667,7 +3672,8 @@ sub config_to_command {
>   	    push @$devices, '-blockdev', print_pbs_blockdev($pbs_conf, $pbs_name);
>   	}
>   
> -	my $drive_cmd = print_drive_commandline_full($storecfg, $vmid, $drive, $pbs_name);
> +	my $drive_cmd = print_drive_commandline_full(
> +	    $storecfg, $vmid, $drive, $pbs_name, min_version($kvmver, 6, 0));
>   
>   	# extra protection for templates, but SATA and IDE don't support it..
>   	my $read_only = PVE::QemuConfig->is_template($conf)
> @@ -4081,7 +4087,9 @@ sub qemu_objectdel {
>   sub qemu_driveadd {
>       my ($storecfg, $vmid, $device) = @_;
>   
> -    my $drive = print_drive_commandline_full($storecfg, $vmid, $device);
> +    my $kvmver = get_running_qemu_version($vmid);
> +    my $io_uring = min_version($kvmver, 6, 0);
> +    my $drive = print_drive_commandline_full($storecfg, $vmid, $device, undef, $io_uring);
>       $drive =~ s/\\/\\\\/g;
>       my $ret = PVE::QemuServer::Monitor::hmp_cmd($vmid, "drive_add auto \"$drive\"");
>   
> diff --git a/test/cfg2cmd/pinned-version-pxe-pve.conf.cmd b/test/cfg2cmd/pinned-version-pxe-pve.conf.cmd
> index fd87f80..095b72e 100644
> --- a/test/cfg2cmd/pinned-version-pxe-pve.conf.cmd
> +++ b/test/cfg2cmd/pinned-version-pxe-pve.conf.cmd
> @@ -23,10 +23,10 @@
>     -device 'virtio-rng-pci,rng=rng0,max-bytes=1024,period=1000,bus=pci.1,addr=0x1d' \
>     -device 'virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3' \
>     -iscsi 'initiator-name=iqn.1993-08.org.debian:01:aabbccddeeff' \
> -  -drive 'if=none,id=drive-ide2,media=cdrom,aio=threads' \
> +  -drive 'if=none,id=drive-ide2,media=cdrom,aio=io_uring' \
>     -device 'ide-cd,bus=ide.1,unit=0,drive=drive-ide2,id=ide2,bootindex=200' \
>     -device 'virtio-scsi-pci,id=scsihw0,bus=pci.0,addr=0x5' \
> -  -drive 'file=/var/lib/vz/images/8006/vm-8006-disk-0.raw,if=none,id=drive-scsi0,discard=on,format=raw,cache=none,aio=native,detect-zeroes=unmap' \
> +  -drive 'file=/var/lib/vz/images/8006/vm-8006-disk-0.raw,if=none,id=drive-scsi0,discard=on,format=raw,cache=none,aio=io_uring,detect-zeroes=unmap' \
>     -device 'scsi-hd,bus=scsihw0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0,id=scsi0,bootindex=100' \
>     -netdev 'type=tap,id=net0,ifname=tap8006i0,script=/var/lib/qemu-server/pve-bridge,downscript=/var/lib/qemu-server/pve-bridgedown,vhost=on' \
>     -device 'virtio-net-pci,mac=A2:C0:43:77:08:A1,netdev=net0,bus=pci.0,addr=0x12,id=net0,bootindex=300,romfile=pxe-virtio.rom' \
> diff --git a/test/cfg2cmd/pinned-version-pxe.conf.cmd b/test/cfg2cmd/pinned-version-pxe.conf.cmd
> index 215df3a..5f738f3 100644
> --- a/test/cfg2cmd/pinned-version-pxe.conf.cmd
> +++ b/test/cfg2cmd/pinned-version-pxe.conf.cmd
> @@ -21,10 +21,10 @@
>     -device 'VGA,id=vga,bus=pcie.0,addr=0x1' \
>     -device 'virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3' \
>     -iscsi 'initiator-name=iqn.1993-08.org.debian:01:aabbccddeeff' \
> -  -drive 'if=none,id=drive-ide2,media=cdrom,aio=threads' \
> +  -drive 'if=none,id=drive-ide2,media=cdrom,aio=io_uring' \
>     -device 'ide-cd,bus=ide.1,unit=0,drive=drive-ide2,id=ide2,bootindex=200' \
>     -device 'virtio-scsi-pci,id=scsihw0,bus=pci.0,addr=0x5' \
> -  -drive 'file=/var/lib/vz/images/8006/vm-8006-disk-0.raw,if=none,id=drive-scsi0,discard=on,format=raw,cache=none,aio=native,detect-zeroes=unmap' \
> +  -drive 'file=/var/lib/vz/images/8006/vm-8006-disk-0.raw,if=none,id=drive-scsi0,discard=on,format=raw,cache=none,aio=io_uring,detect-zeroes=unmap' \
>     -device 'scsi-hd,bus=scsihw0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0,id=scsi0,bootindex=100' \
>     -netdev 'type=tap,id=net0,ifname=tap8006i0,script=/var/lib/qemu-server/pve-bridge,downscript=/var/lib/qemu-server/pve-bridgedown,vhost=on' \
>     -device 'virtio-net-pci,mac=A2:C0:43:77:08:A1,netdev=net0,bus=pci.0,addr=0x12,id=net0,bootindex=300,romfile=pxe-virtio.rom' \
> diff --git a/test/cfg2cmd/pinned-version.conf.cmd b/test/cfg2cmd/pinned-version.conf.cmd
> index 6b01dcf..e072491 100644
> --- a/test/cfg2cmd/pinned-version.conf.cmd
> +++ b/test/cfg2cmd/pinned-version.conf.cmd
> @@ -21,10 +21,10 @@
>     -device 'VGA,id=vga,bus=pcie.0,addr=0x1' \
>     -device 'virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3' \
>     -iscsi 'initiator-name=iqn.1993-08.org.debian:01:aabbccddeeff' \
> -  -drive 'if=none,id=drive-ide2,media=cdrom,aio=threads' \
> +  -drive 'if=none,id=drive-ide2,media=cdrom,aio=io_uring' \
>     -device 'ide-cd,bus=ide.1,unit=0,drive=drive-ide2,id=ide2,bootindex=200' \
>     -device 'virtio-scsi-pci,id=scsihw0,bus=pci.0,addr=0x5' \
> -  -drive 'file=/var/lib/vz/images/8006/vm-8006-disk-0.raw,if=none,id=drive-scsi0,discard=on,format=raw,cache=none,aio=native,detect-zeroes=unmap' \
> +  -drive 'file=/var/lib/vz/images/8006/vm-8006-disk-0.raw,if=none,id=drive-scsi0,discard=on,format=raw,cache=none,aio=io_uring,detect-zeroes=unmap' \
>     -device 'scsi-hd,bus=scsihw0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0,id=scsi0,bootindex=100' \
>     -netdev 'type=tap,id=net0,ifname=tap8006i0,script=/var/lib/qemu-server/pve-bridge,downscript=/var/lib/qemu-server/pve-bridgedown,vhost=on' \
>     -device 'virtio-net-pci,mac=A2:C0:43:77:08:A1,netdev=net0,bus=pci.0,addr=0x12,id=net0,bootindex=300' \
>