[Libosinfo] RFC: Add clock/timers info in osinfo-db

[Daniel P. Berrangé]

On Tue, Jan 22, 2019 at 03:54:17PM +0100, Martin Sivak wrote:
> > So we can
> > have some profiles that are generic best practice for the guest +
> > hypervisor combination.
> 
> I probably still do not understand where is the line between osinfo a
> profiles then. What you are talking about (hypervisor + guest OS)
> seems to me to belong to osinfo.
> 
> Profiles we asked Martin for (as the primary request was probably
> driven from us at the beginning) were really ment to be used for
> workload specific settings on top or in combination with osinfo
> (io-intensive, SAP HANA, OracleDB, ...).

Traditionally lots of logic around how to build a libvirt domain XML
to configure a guest according to best practice for a given deployment
scenario was embedded in applications as code. This was always
undesirable since it caused logic duplication across mgmt apps.

Libosinfo dealt with a small piece of this by allowing optimal
virtual devices to be identified via the DB.

Long ago there was an abortive attempt to address the more general
problem of writing XML via an set of APIS (libvirt-designer +
libvirt-builder). This failed as a concept for various reasons, not
least that doing it via an API is quite inflexible.

The logic that apps hardcoded for configuring a guest OS XML was
usually aiming at an design that was "general purpose" good enough
for any workload, but not optimal for every workload. Apps could
have added app specific logic to optimize for SAP, Oracle, etc
but that just makes the existing problem of hardcoded logic even
worse.

Having a concept of OS profiles in libosinfo is intended to address
the problem of apps all harcoding rules for building XML configs
in the general case. By providing such a feature we could reduce
the amount of harcoded logic in applications, and by extension this
will also make it trivial to provide profiles that are optimized
for specific applications, alongside the general purpose guest
OS profile. 

IOW there should not be any distinction between the way we deal
with a general purpose profile for a guest OS, from the way we
deal with an SAP or Oracle optimized profile for a guest OS. I
would consider it a big failure if we had different ways to
handle the general purpose config vs the application optimized
config.

Regards,
Daniel
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