At Mon, 05 Apr 2021 13:39:45 -0700, "Greg A. Woods" <woods%planix.ca@localhost> wrote:
Subject: Re: trouble running FreeBSD with Xen-4.13 (including weird performance issues)
>
> I don't think that turning of some of the vulnerability mitigations
> helped with the weird performance issues I see with FreeBSD domUs on
> some older hardware:
>
> menu=Boot Xen:load /netbsd-XEN3_DOM0 -v bootdev=dk0 console=xencons;multiboot /xen bootscrub=false dom0_mem=4G console=com1,vga console_timestamps=datems dom0_max_vcpus=4 dom0_vcpus_pin=true pv-l1tf=off,domu=off l1d-flus=off vpmu=on
>
>
> It still took an enormously long time to get the installer running:
>
> # xl list
> Name ID Mem VCPUs State Time(s)
> Domain-0 0 4096 4 r----- 125.3
> fbsd-test 1 1936 4 -b---- 1553.3
Hmmm.... If you look closely at the Xen command line above you'll notice
a small typo ("l1d-flus" should have been "l1d-flush" of course).
This has helped me separate out two different tests!
So fixing that did shave a lot off the boot time, but not nearly enough:
# xl list
Name ID Mem VCPUs State Time(s)
Domain-0 0 4096 4 r----- 73.6
fbsd-test 1 1936 4 -b---- 1093.9
Looking back earlier just after boot I see the dom0 took only 55 CPU
seconds to get to full multi-user and have me open some xterms and start
the boot of the FreeBSD test (here the FreeBSD instance has already
started init but isn't far into its /etc/rc run):
# xl list # XXX from much earlier than the run just above
Name ID Mem VCPUs State Time(s)
Domain-0 0 4096 4 r----- 55.3
fbsd-test 1 2000 4 r----- 34.8
Meanwhile the 1093 seconds above for FreeBSD (and 1553 without
l1d-flush=off) is just to get to the prompt where the installer asks
what kind of terminal you're using.
With 73 seconds used the dom0 already has two emacs sessions open and
I'm beginning to load my mailer in one of them!
--
Greg A. Woods <gwoods%acm.org@localhost>
Kelowna, BC +1 250 762-7675 RoboHack <woods%robohack.ca@localhost>
Planix, Inc. <woods%planix.com@localhost> Avoncote Farms <woods%avoncote.ca@localhost>
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