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Re: [Xen-devel] [win-pv-devel] Question about windows domU long boot time in xen and help for update libxl virtio patch (for a test)

Il 08/05/2015 16:59, Paul Durrant ha scritto:
-----Original Message-----
From: win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx [mailto:win-pv-devel-
bounces@xxxxxxxxxxxxxxxxxxxx] On Behalf Of Fabio Fantoni
Sent: 08 May 2015 15:54
To: xen-devel; win-pv-devel@xxxxxxxxxxxxxxxxxxxx
Cc: Anthony Perard; Wei Liu; Ian Campbell; Stefano Stabellini
Subject: [win-pv-devel] Question about windows domU long boot time in
xen and help for update libxl virtio patch (for a test)

In latest years hvm domUs support and performance was increased but
windows boot time is still too long.
I tried out all sort of combinations (without pv, with old gplpv and new
winpv, with vnc, spice or without both, with different vgas and many
other options) with same result: strange long boot time (before arrive
to user login).
On kvm (trying with same qemu/seabios versions, qdisk with raw ecc...)
instead for example the boot time is faster and similar to the phisical
pc one with same vcpu ram ecc as assigned.
Is there something that need to be improved/fixed in windows pv drivers
or xen?

Which version of QEMU are you using. I tend to use upstream, but I see a *very* 
long pause between the end of firmware logging and sampling the viridian cpuid 
leaves (which is generally the next thing to cause some logging) so my 
suspicion is that the int13 handling in seabios is probably the culprit. That's 
only a hunch, but using rombios and qemu trad is quite a lot faster.

Thanks for reply.
With qemu-trad if I remember good was faster on initial boot but have lower general performance, I don't use anymore qemu-trad on dom0 with xen >= 4.3 About qemu upstream I started use it on 1.2 if I remember good and after I always tested all versions up to 2.2 and seabios I keeped updated rebuilding from debian sid package (now 1.8.1)

Once the kernel starts to boot I see no significant delays. PV drivers are not 
wonderfully fast to start up as the xenstore state dance does take a while. It 
is somewhat unavoidable though.


I tried to narrow down my search trying with virtio disk on xen but I
was unable to have libxl patch working.
I taken very old Wei Liu patch from here:

And I tried to adapt it but there is something that I not understand and
causing the build fails:
libxl.c:2339:32: error: LIBXL__DEVICE_KIND_VIRTIO undeclared (first use
in this function)

Here the path I updated and tried failing, I did only disks part (nic
need only model change in xl.cfg FWIK):

Can someone help me to complete/fix it please?

Thanks for any reply and sorry for my bad english.

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