[KLUG Programming] Pthreads problem

[Adam Williams]

> > > `cat /proc/slabinfo` shows you things `sysctl -a` will not. This
> > > kind of kernel publishing doesn't fit in current sysfs and sysctl
> > > would be awkward and suffer from poor discovery.
> > Sure but this is just a shortcoming in Linux overall, and why AIX
> > kicks-its-a$$ as far as managability goes.  No places holds
> > "everything".  Tuning an OS like AIX is much more a step-by-step
> > procedure than tuning "cancerous" :) Linux.
> If you think echo and /proc are the sources of that, I suggest you're
> high.
> Cathedral v. bazaar: changes in AIX pass through committees which ensure
> that important commercial apps won't have to change too quickly.  In

Well, then in this case the Cathedral wins hands down; 'cause those
priests got game.

> Linux, even 2.4 from Red Hat sees RH backporting features like crazy:
> ALSA, NPTL, O(1) schedulers. Stable? Hah!

It is surprisingly stable - not as stable as an OS like AIX - but not
too far behind.  Most Linux stability issues I encounter are with
handling hardware; well, that and crappy versions of nscd.

> Also, how exactly do you tune AIX? (Never having been root on one, I
> wouldn't know.) Do you use big, expensive apps specifically written by
> IBM to control their big, expensive OS? Do you think you might be
> reduced to echo, or sysctl, if you didn't have those apps? Hmmm....

AIX tuning is performed at the command line using five command line
utilities; they support both querying and modifying values.
ioo - The I/O subsystem
nfso - The RPC subsystem
no - The network subsystem
vmo - The virtual machine 
schedo - The schedular
They all take identical command parameters and behave the same way and
have the same exit values, etc...

> I have not yet read the kernel code yet (but plan to) to verify that
> echo can break things sysctl cannot; even so, someone who wished to
> create a comprehensive library of permissible sysctl changes is chasing
> a unicorn: echo(1) is not their greatest problem by a long shot.
> Tracking new values and obsoleting old ones, and verifying
> correct/incorrect/buggy values, is their bete noir.

That may be THEIR problem,  mine is quite different.  I need to
establish a system, and perform updates, without tuning and
configuration getting silently elided (or crapping my system).

> Such a system would almost certainly use sysctl(2) directly for
> efficiency, rather than calling it indirectly through the VFS.
> Efficiency for such a (fictional) /proc-management app would be quite
> different than for a hacker at the keyboard, or a script that changed
> some value while doing network migration. 

Fictional? http://powertweak.sourceforge.net/index.html  This app is a
nice way to initially navigate system values.  Wouldn't trust in on one
of my servers.

> > I don't think it is anywhere near 'cannonical truth' that "sysctl =
> > good" and "echo {} > /proc/{}" bad.
> What's the canonical spelling of canonical? Oh, yeah.... ;-)

Depends on what you mean.  The guy with the biggest cannon decides what
is canonical.