Guys,
Please revisit the dynamic linking for everything. The
cost for using shared libs in cases like shells actually
is higher than statically linking (both in memory and
in time.) It appears that there is a loss of VM understanding
over time. Don't confuse the advantages of using shared
libs on X windows (and environments like that) with the
same advantages being non-existant when using shared
libs on normal layout programs (shells are perhaps the
worst general case, but not necessarily the worst in all ways.)
Another issue: if you continue to support the dynamic
linking mechanisms for special shared libs, but otherwise
link statically, much of the high overhead of shared libs
for-everything will still be mitigated. Just because there
might be a need for a special shared lib, that doesn't justify
using shared libs for everything (and add the cost of
sparse memory allocation and significantly higher fork/exec
times than necessary.) For a 'fun time', take a look at
the process map in the deprecated /proc filesystem. Compare
the size (complexity) of a shared program with a static
program... It doesn't show all of the internal differences,
but is an externally accessable (and benchmark free) exemplar.
The only real reason for building various programs dynamic
in order to gain the advantage of specific shared object
would be an all or nothing type argument (a typical fallacy
in most religious discussions.)
It really doesn't make sense to arbitrarily cut-off a
discussion especially when a decision might be incorrect.
Perhaps the all-dynamic scheme had been decided upon so
as to give a competitive performance advantage to those who
rebuild everything (appropriate) static? :-).
If there hadn't been a noticed increase in cost by using
all-shared-libs, then the measurements were done
incorrectly. If the decision is made based upon allowing
for 1.5X (at least) times increase in fork/exec times, and
larger memory usage (due to sparse allocations), then it
would be best to have decided that performance isn't as
important as it used to be (which it just might not be
anymore.) Last time that I heard, disk space is still
much much less expensive than main memory :-).
Remember: the cost for disk space is nil nowadays, space
only made obvious by an insanely small default root filesystem
size allocation. (An 'insanely' small root filesystem is
okay when that root is a mini-root recovery system, but
the cost of an extra 500MB is rather small on a non-specialty
system is nil compared to other resources.)
I do use an all-dynamic configuration for certain embedded
applications (but also a case where there are no seperated
filesystems, and the memory usage isn't quite as important
because of the fact that AVAILABLE features is more important
than lots of concurrently running programs.) For the best
sharing and quickest system response (both due to memory and
raw program/image invocation times), at least make the shells
static.
(Sorry for any misspellings or grammar errors -- it is early
in the morning... I'll probably not participate in any further
discussion on this matter either, but it would be good to
generally avoid loosing 'ancient', but still 'accurate'
technical history.)
John
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