Re: [win-pv-devel] load+stability tests result: Event 129 xenvbd, benchmark regression

[Andreas Kinzler <ml-ak@xxxxxxxxx>]

Hello Paul,

thanks - logging is now working. However, I paused the stability tests 
mentioned in my original email because there is a serious performance 
regression when switching from dom0 kernel 3.10 to 4.8. Here are some 
results of my benchmarks: it tests all 4 combinations of dom0 either 
3.10 or 4.8 and PV driver either citrixpv 8.2-rc2 or GPLPV. citrixpv is 
only a bit slower on 3.10 but totally breaks on 4.8. Can you think of 
any reason for that?
xen 4.8, kernel 3.10.73, win81, citrixpv, ? VCPUs, ramdisk in dom0
pass #  309: emptyDir... done (1313 msec) writing... done (46821 msec, 
961.1 MB/sec) reading... done (24055 msec, 1870.7 MB/sec)
pass #  310: emptyDir... done (1331 msec) writing... done (47347 msec, 
950.5 MB/sec) reading... done (24164 msec, 1862.5 MB/sec)
xen 4.8, kernel 3.10.73, win81, gplpv, 4 VCPUs, ramdisk in dom0
pass #    5: emptyDir... done (1316 msec) writing... done (44257 msec, 
1017.3 MB/sec) reading... done (23763 msec, 1894.7 MB/sec)
pass #    6: emptyDir... done (1239 msec) writing... done (44344 msec, 
1015.1 MB/sec) reading... done (23629 msec, 1905.1 MB/sec)
xen 4.8, kernel 4.8.17, win81, gplpv, 4 VCPUs, ramdisk in dom0
pass #  148: emptyDir... done (1269 msec) writing... done (41125 msec, 
1094.2 MB/sec) reading... done (23542 msec, 1911.4 MB/sec)
pass #  149: emptyDir... done (1193 msec) writing... done (41259 msec, 
1090.8 MB/sec) reading... done (23916 msec, 1881.9 MB/sec)
xen 4.8, kernel 4.8.17, win81, citrixpv, 4 VCPUs, ramdisk in dom0
pass #    1: emptyDir... done (0 msec) writing... done (55009 msec, 
818.5 MB/sec) reading... done (136126 msec, 330.7 MB/sec)
pass #    2: emptyDir... done (1356 msec) writing... done (57478 msec, 
783.1 MB/sec) reading... done (101489 msec, 443.5 MB/sec)
Regards Andreas

On 25.01.2017 12:32, Paul Durrant wrote:
> > -----Original Message-----
> > From: Andreas Kinzler [mailto:ml-ak@xxxxxxxxx]
> > Sent: 24 January 2017 16:28
> > To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> > Subject: Re: [win-pv-devel] load+stability tests result: Event 129 xenvbd
> >
> > I tried 'xl debug-keys q' but nothing is written to the qemu log? I am using the
> > release build of win-pv. Do I need a debug build of win-pv ?
> No, I suspect the issue is with your QEMU. I assume you are using upstream? If 
> so then you need to enable the appropriate trace event. This is what I do...
>
> Create a file called 'events' somewhere and put the following line in it:
>
> xen_platform_log
>
> Then, in the xl.cfg for your VM, add the following line:
>
> device_model_args=[ "-trace", "events=<path to your events fie>" ]
>
> You should then see logging from the PV drivers when you boot the VM, and when 
> you do 'xl debug-keys q'.
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