[ovirt-users] Re: Different cpu flags preventing live migration
On Mon, Mar 2, 2020 at 4:51 PM Michal Skrivanek <michal.skrivanek(a)redhat.com>
wrote:
>
> I have this cpu flag set: invpcid_single
>
> Instead on the same host in 4.3.5 (eg kernel 3.10.0-1062.el7.x86_64) the
flag is not set.
sometimes there are kernel changes like that, but more usually it’s just
the microcode version on each host (not bios), did you check that too?
I do think so too. The microcode update from 4.3.5 to 4.3.8 consists in
microcode_ctl passing from microcode_ctl-2.1-53.el7.x86_64 to
microcode_ctl-2.1-53.7.el7_7.x86_64.
And in the mean time this solution has been created, that confirms the flag
introduced for Meltdown mitigations:
https://access.redhat.com/solutions/4866021
> Now you can remove the "Pass-Through Host CPU" flag
--> remove it
but then you’re losing probably the biggest differentiator for “high
performance”, so then maybe not use that profile at all?
Yes, you are right ;-) I used it mainly for enabling I/O threads and
testing on huge pages (and different icon display ...)
Gianluca
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