[TUHS] Do Interface specifications such POSIX or the LSB Still Matter

Larry McVoy lm at mcvoy.com
Sun Feb 18 11:01:58 AEST 2018


On Fri, Feb 16, 2018 at 01:36:14PM -0500, Clem Cole wrote:
> On Fri, Feb 16, 2018 at 10:45 AM, Larry McVoy <lm at mcvoy.com> wrote:
> > Meh, not really.  Until Git ate our market, we supported everything you
> > might imagine.  Windows, MacOS, Linux-{x86,x86_64,sparc,ppc,itanium,mips},
> > AIX, IRIX, HP-UX, Solaris.
> >
> > Source base of 2.6 million lines of code and docs.
> >
> ???Did you have messaging (Co-Arrays, MPI or SHMEM) mixed in?  I'm guess
> not., but your system is (was) extensive so I'm asking....

Nope.  We did our own protocol over TCP and HTTP.

> >  We limited our stuff to very basic stuff
> >
> ???Yup -- very wise.   Simple library to insulate you from OS.
> Did you shipped statically bound or use *.so's

We could build static, we had a "make crank-static", but we rarely did
that, it was only for some oddball targets.  99.9999% of the time it
was dynamic and it was not a problem because I was so careful about
what we used in libc (as I said before, it was only in the last 5 years
that I trusted that realloc() actually worked).

> Also how much are you dependant on OS databases (password & credential
> libraries and other things  stored in /etc, /usr/lib or /var)????
> ???This is were even within Linux, life can get messy pretty fast.???

We really didn't use much, we were not parsing that stuff for the most
part.  There were some things we did, for example, we have a fstype()
function that called disktype().  It tried to find the mount point,
looking through

	/etc/mtab
	/etc/mnttab
	/var/log/mount.today

and it figured out if it was NFS or not.  If it was not NFS then it 
called disktype which tried to figure out if it was SSD or not by 
pawing through stuff like /sys/block/%s/queue/rotational

All of that was so we could auto-optimize parallelism, NFS wants 8 way,
SSD wants all the CPUS, rotating disk wants just one or you thrash the
arm.

> > Netflix does a lot in AWS.  And they care about performance.  But they
> > code around the variance that you get from containers, I could see that
> > as an issue for the old school fortran people.
> >
> ???Good .. you get it.???

Maybe.

> > I'm sort of struggling to see what problem it is you want to solve.
> >
> ???Without revealing the ISV, I know very well know HPC ISV that used to have
> a >>Linux<< only test matrix of over 140 perminations before they could
> release and they only supported RH and SuSE.   But between different
> manufacturers, distributed file systems, interconnect, messaging stacks,
> compilers *et al???*
> 
> *??? *it got messy very fast.???

I really don't see why.  I can see why if they are using every library
known to man, but if you want portable you don't do that.


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