From: "Wei D Chen" <wei.d.chen(a)intel.com>
To: "Doron Fediuck" <dfediuck(a)redhat.com>, "Ofri Masad"
Sent: Friday, March 29, 2013 5:00:55 AM
Subject: Re: [Engine-devel] Open Attestation integration with oVirt engine proposal has
submitted patchset5 for your
Thanks Doron & Ofri,
As to the question of cache flash, we already have our consideration and
wrote them on our design page. I have no doubt that your suggestion is more
reasonable, we just keep in mind that expiration is much longer that the
time needed to poll all of hosts, so this is really a potential issue we
ignored. Let's make estimation at first, we will have a try if our schedule
Doron, we have reserved some effort to research about cluster-level policy.
As ovirt is complete new to our engineers, would we finished our current
features (such as ovf and rest api.) in pipeline at first? After these basic
features are ready and we still have some buffer, we will make some
improvement. Is this acceptable?
Thanks again to Doron and Ofri.
From: Doron Fediuck [mailto:firstname.lastname@example.org]
Sent: Thursday, March 28, 2013 10:43 PM
To: Ofri Masad
Cc: engine-devel(a)ovirt.org; Chen, Wei D
Subject: Re: [Engine-devel] Open Attestation integration with oVirt engine
proposal has submitted patchset5 for your review
----- Original Message -----
> From: "Ofri Masad" <omasad(a)redhat.com>
> To: "Wei D Chen" <wei.d.chen(a)intel.com>
> Cc: engine-devel(a)ovirt.org
> Sent: Thursday, March 28, 2013 12:05:02 PM
> Subject: Re: [Engine-devel] Open Attestation integration with oVirt
> engine proposal has submitted patchset5 for your review
> Hi Dave,
> I would like to raise again the question of the full cache flash for
> each stale cache entry found.
> This method can cause two unwanted situations:
> 1. Choosing untrusted host: lets say, for example that you have 1000
> host in your pool. you look at the first host in the cache and find
> that its attestation hat expired. you refresh the entire pool (there
> are 1000 host, that must take some time). by the the time the last
> host was refreshed in the pool, the first host may already be expired
> again. but since you already checked it - you keep on with your flow
> and select that host, even so it has expired and may as well be
> 2. infinite loop: lets say we'll try to fix what I've described in
> 1. then, we need to check again if the host has expired before we
> select it. if it is, the entire refresh process starts again. this
> could potentially go on forever (unless I'm missing something, and
> the expiration is much longer then the full re-cache process).
> Instead of re-caching the full cache we can do as follows:
> - hold the cache entries sorted by expiration (if the expiration
> time is the same for all hosts, so a queue is enough).
> - each time we need a new trusted host - select from the unexpired
> hosts, refresh all expired hosts (in one query).
> - if all hosts are expired - we can wait for the first host to be
> defined trusted by the attestation server and select that host.
Dave, adding another suggestion on top of Ofri's;
Generally speaking, a cluster of hosts defines many joint features (such as
CPU level), which means that in the same cluster we would expect to be able
to freely migrate a VM from one host to another.
Current trust-pools design is breaking this concept, as you introduce a state
where a VM cannot migrate from a 'safe' host into an 'unsafe'
This leads me to the suggestion of having attestation as a cluster policy
rather than a VM-level property. It means that all hosts in this cluster are
constantly being monitored to be safe. If a host is declared as unsafe in
the Attestation server, it will become non-operational in the engine. This
will simplify the implementation since you have everything ready for you
once you have a 'safe' cluster and no need to do any VM-level changes.
So in this way you keep current concepts while simplifying the implementation
with very little worries of performance issues.
Can you please share your thoughts on this suggestion?
> ----- Original Message -----
> > From: "Wei D Chen" <wei.d.chen(a)intel.com>
> > To: engine-devel(a)ovirt.org
> > Sent: Friday, March 22, 2013 11:34:55 AM
> > Subject: [Engine-devel] Open Attestation integration with oVirt
> > engine proposal has submitted patchset5 for your review
> > Hi all,
> > Before submitting this patch set, we has updated our design page,
> > and new feature about VM template has added to this patchset. In
> > patchset a lot of frontend changes has been imported.
> > Welcome to review our patchset and thanks advance for your
> > suggestion.
> > Detailed description: http://wiki.ovirt.org/Trusted_compute_pools
> > In this patch set, follow changes has been introduced:
> > 1. GUI changes to support for creating a trusted VM on a trusted
> > physical host.
> > 2. View/Edit VM changes to enable end user switch between three run
> > on options.
> > 3. Template relevant changes to support end user create a trusted VM
> > template and create trusted VM based on this template afterwards.
> > 4. Bug fixing and code cleanup.
> > 5. wiki design page update.
> > Best Regards,
> > Dave Chen
Hi, I read your design and I have some proposal about implementation of cache.
Currently in project we have couple of places with custom-made cache implementation,
my advice is to start using something that already written and well tested:
I think that cache of Guava project (
) is good
The following cache has all required functionality and some features that can help for
like Removal Listeners (sync/async) and cache Loaders, also the following implementation
is easy to configure and test.
The code for cache can be put inside utils.
Also, not sure that is a relevant but the following stuff can influence your feature:
remove of host, add of new host,
moving a host to maintenance and after that to other cluster/pool, host restarts