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<div class="moz-cite-prefix">
<div class="moz-cite-prefix">In my (not particularly significant)
experience that question never seems to produce a consistent
answer and certain
drive performance has noticeably changed for the better in
recent versions so it's all a moving target. I do know if=virtio
is considered the legacy approach vs if=none because even though
it is usually identical it doesn't create implicit controllers.<br>
<br>
Unless somebody up to date saves us I think you will have to
test it yourself. I recently did the least amount of testing
possible and was surprised to find the ide driver on qemu 2.5
and recent OVMF to be near bare metal with an AHCI controller
(it is basically passthrough AHCI now I think).<br>
<br>
-drive
if=none,format=qcow2,cache.direct=on,file=$KUBIMG,aio=native,id=windrive<br>
-device ide-hd,bus=ide.0,drive=windrive,bootindex=0<br>
<br>
But the newest and clearest winner for me is block device virtio
on raw disks / block devices. It performed exactly like bare
metal with the intel rapid store drivers on random 4k (80Mb/s),
queues and throughput but I haven't taken the time to pull it
apart or repeat the test. IIt uses msi-x, request combining,
multiqueues and iothreads which makes it my official guess for
the latest and greatest.<br>
<br>
-drive
if=none,format=raw,cache=none,cache.direct=on,file=/dev/sdb,aio=native,id=ssd2,discard=off,detect-zeroes=off"<br>
-object iothread,id=iothread2"<br>
-device
virtio-blk-pci,drive=ssd2,request-merging=on,iothread=iothread2,modern-pio-notify=on,config-wce=off<br>
<br>
I did find a write up describing it's development but I can't
seem to find it again (it's a scsi controller). Not much written
about it but I can give you my start up scripts / versions /
performance stats if you try them and they are stupid slow. Try
a recent qemu too if you don't already.<br>
<br>
On 02/04/16 21:37, Nick Sarnie wrote:<br>
</div>
<blockquote
cite="mid:CAOcCaLYs4-d+XyxVT-FRiO-yqZvn6EzMfGBuAOqeq3yd7EQpzQ@mail.gmail.com"
type="cite">
<div dir="ltr">
<div>
<div>Hi guys,<br>
<br>
</div>
It seems the biggest limiting factor of my GPU Passthrough
setup is the disk. Does anyone have any tips to optimize it?
Also, which is faster, having the disk with if=virtio, or
having the disk with if=none and a virtio SCSI controller.
The raw image is 250GB on a 500GB ext4 hard drive, which is
encrypted with dm-crypt. Below is my current script. <br>
<br>
Thanks,<br>
</div>
Sarnex<br>
<br>
<br>
#!/bin/sh<br>
export QEMU_AUDIO_DRV=pa<br>
qemu-system-x86_64 -enable-kvm \<br>
-m 5120 \<br>
-cpu host \<br>
-smp 8,sockets=1,cores=8,threads=1 \<br>
-device vfio-pci,host=01:00.0,x-vga=on,multifunction=on \<br>
-device vfio-pci,host=01:00.1 \<br>
-vga none \<br>
-drive
file=/media/500GB/win10.img,id=disk,if=virtio,cache=none,format=raw
\<br>
-device vfio-pci,host=00:12.0 \<br>
-device vfio-pci,host=00:12.2 \<br>
-device vfio-pci,host=00:16.0 \<br>
-device vfio-pci,host=00:16.2 \<br>
-soundhw ac97 \<br>
-rtc base=localtime \<br>
-netdev user,id=net0 \<br>
-device virtio-net-pci,netdev=net0 \<br>
-device virtio-scsi-pci,id=scsi <br>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
vfio-users mailing list
<a class="moz-txt-link-abbreviated" href="mailto:vfio-users@redhat.com">vfio-users@redhat.com</a>
<a class="moz-txt-link-freetext" href="https://www.redhat.com/mailman/listinfo/vfio-users">https://www.redhat.com/mailman/listinfo/vfio-users</a>
</pre>
</blockquote>
<br>
<br>
On 02/04/16 21:37, Nick Sarnie wrote:<br>
</div>
<blockquote
cite="mid:CAOcCaLYs4-d+XyxVT-FRiO-yqZvn6EzMfGBuAOqeq3yd7EQpzQ@mail.gmail.com"
type="cite">
<meta http-equiv="Context-Type" content="text/html; charset=UTF-8">
<div dir="ltr">
<div>
<div>Hi guys,<br>
<br>
</div>
It seems the biggest limiting factor of my GPU Passthrough
setup is the disk. Does anyone have any tips to optimize it?
Also, which is faster, having the disk with if=virtio, or
having the disk with if=none and a virtio SCSI controller. The
raw image is 250GB on a 500GB ext4 hard drive, which is
encrypted with dm-crypt. Below is my current script. <br>
<br>
Thanks,<br>
</div>
Sarnex<br>
<br>
<br>
#!/bin/sh<br>
export QEMU_AUDIO_DRV=pa<br>
qemu-system-x86_64 -enable-kvm \<br>
-m 5120 \<br>
-cpu host \<br>
-smp 8,sockets=1,cores=8,threads=1 \<br>
-device vfio-pci,host=01:00.0,x-vga=on,multifunction=on \<br>
-device vfio-pci,host=01:00.1 \<br>
-vga none \<br>
-drive
file=/media/500GB/win10.img,id=disk,if=virtio,cache=none,format=raw
\<br>
-device vfio-pci,host=00:12.0 \<br>
-device vfio-pci,host=00:12.2 \<br>
-device vfio-pci,host=00:16.0 \<br>
-device vfio-pci,host=00:16.2 \<br>
-soundhw ac97 \<br>
-rtc base=localtime \<br>
-netdev user,id=net0 \<br>
-device virtio-net-pci,netdev=net0 \<br>
-device virtio-scsi-pci,id=scsi <br>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
vfio-users mailing list
<a class="moz-txt-link-abbreviated" href="mailto:vfio-users@redhat.com">vfio-users@redhat.com</a>
<a class="moz-txt-link-freetext" href="https://www.redhat.com/mailman/listinfo/vfio-users">https://www.redhat.com/mailman/listinfo/vfio-users</a>
</pre>
</blockquote>
<br>
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