[gentoo-user] Re: make oldconfig ?

[James]

Tom H <tomh0665 <at> gmail.com> writes:


> >> /usr/src/linux/scripts/kconfig/Makefile
> >> /usr/src/linux/scripts/kconfig/conf.c

> I'm not too sure what you're looking for but if you want to compare
> config_new and config_old where you generated config_new with
> config_old and "make oldconfig", you can use "./scripts/diffconfig
> .config config.old".


Background::
I have been researching and reading about a plethora of cluster/cloud
approaches to running normal linux codes (frameworks if you like) and also
Hi Performance Computing (many machines on a single problem). Long story
short version, it seems the more the linux system is minimized, in size and
complexity, the faster the containers or HPC applications run on top of it
and the easier it is to 'secure' the cluster. Many, in the cluster world,
particularly the HPC folks, are not using systemd as it adds unnecessary
complexity and degrades performance, albeit systemd does bring some ease of
management to large numbers of nodes. Gentoo has quite a following of openrc
folks, as I am one, and there needs to be a openrc pathway to
cluser-paradise, imho. Most folks are keeping their secrets as to how to
best tune a linux kernel for cluster or container deployment. Mix that in
with Systemd complexities and the result is a very obfuscated environment
for kernel tuning and benchmarking of clusters. So I'm going to need tools
to rapidly (CI?) rebuild various linux kernels with minor tweaks to the
config, as well as deployment consistency.

Cluster vendors have basically two strategies:: Commercially offer a version
of the cluster that is tuned to a specific performance need, and/or
commercially offer the very nice management tools that make clustering 
easy, pleasant and robust.


I have become very interested in developing a small cluster for testing some
of the myriad of cluster offerings. IMHO:: a cluster is just a local cloud
that is run locally. So for my example 12 systems, mostly amd64, but some
intel and arm64 systems, are to be used. The desire is to be able to use
these systems, to rapidly throw up a cluster for containers, or HPC, run
some codes, trap and retain data for later analysis and comparison with runs
against other cluster architectures and codes that constitute a given target
cluster. Loosely, cluster benchmarking. 


There is the myriad of 'frameworks' that are available for the various
clusters one can build. It's all quite complex on the surface (vendor
hyperbole), but underneath, vetting performance claims is quite simple. Load
of the test-cluster with codes, run some jobs/apps/codes on a given
cluser+frameworks, collect data for analysis and comparison. 


Present:: 
Gentoo's GSoC has at least two projects that are very appealing to me along
these lines::

1) Stateless Minimal Gentoo

2) kernelconfig

Item two is the tie-in for oldconfig and associated semantics. PXE boot and
other metrics are at play here too. So a comprehensive kernel build and
deploy system, for lots of systems and different architectures, is of
interest. Most prototype work is done on amd64. Live kernel patching is
an active area of development and in some circumstances will not necessitate
the reboot of the system/node to update the kernel [A].

Item one is similar to CoreOS. CoreOS has a system for rapidly deploying
systems from a cold boot as well as live updates to the running OS with
rollback if necessary. Impressive to say the least. But, CoreOS is locked
into the systemd pathway. Myself, being of the minimalistic embedded ilk, I
tend to lean towards the alpine-docker pathway of minimization and
openrc/busybox.


Lofty goals. But, extraordinarily useful to linux folks, especially those
with small to medium size data-centers. Note, lots of folks drop me email
privately with information, concerns and tidbits of wisdom most useful
in my journey to cluster-paradise. Public guidance and even scorn, are also
most welcome. Reams of inexpensive arm64 machines combined with compiler
advances make clustering the most exciting adventure in the linux world, atm.


hth,
James

[A] http://rhelblog.redhat.com/2015/03/23/live-kernel-patching-update/