Re: [Xen-devel] [PATCH] tools/libxl: make default of max event channels dependant on vcpus

[Jürgen Groß <jgross@xxxxxxxx>]

On 26.03.20 10:54, Jan Beulich wrote:
> On 26.03.2020 10:45, Juergen Gross wrote:
> > Today the maximum number of event channels for a guest is defaulting
> > to 1023. For large guests with lots of vcpus this is not enough, as
> > e.g. the Linux kernel uses 7 event channels per vcpu, limiting the
> > guest to about 140 vcpus.
> I don't think any particular guest OS should "dictate" the default
> here. What if another OS (or even a future version of Linux) requires
> more than 8? And why would the value depend on number of vCPU-s but
> not number and kind of virtual devices?
It is a rough estimate. And with HVM guests being limited to 128 cpus
anyway, this problem is more relevant for PV guests, limiting the
available options for guest OS's.

You can always specify a larger value in the guest config after all.


Juergen