Re: static binary timings (Was: Some more patches for GCC on NetBSD/VAX coming soon...)

[David Brownlee <abs%netbsd.org@localhost>]

On 30 March 2016 at 13:45, Johnny Billquist <bqt%update.uu.se@localhost> wrote:
> On 2016-03-30 14:11, Anders Magnusson wrote:
>>
>> Den 2016-03-30 kl. 13:34, skrev David Brownlee:
>>>
>>> Conclusions (albeit with simh timings)
>>> - having makemandb running makes timings (and the machine) pretty much
>>> useless
>>> - NOPAM reduced login time by 33%
>>> - NOPIC reduced login time by 50%
>>> - NOPIC reduced boot time by 25%, even allowing for fixed times such
>>> as kernel boot
>>>
>> This is actually very strange, since the generated assembler is
>> basically the same.
>>
>> Maybe if it's the dynamic linking itself and not PIC that is causing the
>> speed penalty?

My supposition would be that rc.d startup involves a relatively large
number of short lived processes, so any difference in process start up
costs will weight much more heavily. I would expect the performance of
(say) nginx to be much close on static/dynamic

>> It would be interesting to test this on real iron (Johnny? :-)  to see
>> the outcome.
>
> The 8650 is up and running. Just point me to tarballs... :-)
>
> Dynamic linking definitely have costs. All the file opening and symbol
> resolving... But also, just image activation I seem to remember being an
> issue.
>
> Davids tests are interesting, but unfortunately, having login data samples
> at 6,4,3 means we have way too low resoltion and too few samples to draw any
> real conclusions.
>
> And since David asked, yes - I also noticed that makemandb now is run by
> default at boot time. Was a bit surprised by that one myself. :-)

The makemandb is an issue for other ports (eg: m68k, and lower memory
i386). I think we should assume that running makemandb on boot is
entirely inappropriate on vax and just disable it manually for now
while we investigate the static/dynamic.

The old timing images are at http://sync.absd.org/vax/timing-images/,
but I think it would be appropriate to run off a new set with gcc 5.3
:)

Let me get started on that and I'll email back when they're ready.

David