[gentoo-user] Re: jbd2 keeps spinning my disk up

[James]

Peter Humphrey <peter <at> humphrey.ukfsn.org> writes:


> My little Atom box's hard disk spins up every minute or so, and watching
> iotop I see it's jbd2 that does it.

> Google shows that others have similar problems.

> Before I re-create all the partitions as reiserfs - and remove ext4 from the
> kernel - does anyone have a lighter solution?

Well, lots in good responses, so please do not interpret
mine as saying it's a better solution that what
others are suggestion.

Atom is more of an embedded processor than
a true workstation/server processor, imho.
As such, it it more "bare metal" meaning
countless software developments for AMD and
Intel processors intended for workstations
and servers, are irrelevant, useless, harmful,
redundant, or just plain stupid for embedded
processors. like the atom.

So now you (and I and millions of folks) are
trying to use mega-software (linux distro)
on a bare-metal processor....

NOBODY has fleshed out these issues on an itemized
basis. i.e. the knowledge base is sparse (at best)
since the only one that can really do this is the
silicon vendors and they have a VESTED INTEREST
in not doing so. Furthermore, since Atom and ARM
and many other embedded processors are combined
as "cores" on an SOC (system on a chip) each
revision of such hardware by each vendor can have
different addtional hardware on the SOC that a generic
compiled software distro is clueless about.
 That's why numerous devices
that attempt low power linux, use a proprietary
linux based on montaVista or countlesss other
embedded linux vendors. These purveyors and vendors
of the various embedded linux offerings do not
publish anything about these hardware details
for some issues and do include documentation,
deep in the specifications of the processor.

When you stray from that (the linux distro that
come with the product), you are on your own,
finding piecemeal information about low level
hardware intricacies....ad-nossium.....imho.
If the device came with some OS other than a
linux hack..... YOu are much futher from
paradise then with a default linux distro
as the OS the vendor provided. It does not mean
you will not be successful, just your journey
is perilous, at best, if optimization is
what you seek.


Long story short, for years I have been building
firewalls and embedded linux bridges, sniffers
and other passive ethernet based devices,
using ext2. Works beautifully with little
attention. Not optimized, but avoid a HUGE
time-sink.

I encounter a myriad of issues, when trying
newer file systems for embedded linux systems.
Ext-2 works for years on Compact Flash drives
if you do not log, or limit logs to an NFS link
or such. As one reader suggested, you have to
audit, one application at a time, to find the culprit.
It's actually a never ending process, imho,
as feature creep on a myriad of software packages
will usually lead to performance issues and thus
more aggressive algorithms on data movement.

You may want to try some of the file systems
intended for embedded system (as part of the 
newer linux kernels)  and the tuning
parameters therein, if you are looking for
a robust solution. Also delete what you do
not need from the atom based system, just
as a general policy. Minimal and embedded
are different facets of the same thing.

Intel atom is first and foremost an embedded
processor, not a CISC processor. I.E. just
because it compiles, does not mean it runs
well on limited resources or bare metal.


Happy Hunting,
James