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Re: CVS commit: src/sys/arch

Chuck Silvers <> wrote:
> > > Log Message:
> > > map all of physical memory using large pages.
> > > ported from openbsd years ago by Murray Armfield,
> > > updated for changes since then by me.
> > 
> > This is cool, thanks!  Can you add an entry to src/doc/CHANGES?  Also,
> > just wondering - did you try any benchmarks?  I would expect reasonable
> > improvement.
> does it really make sense to list incremental performance improvements
> there? I can add it if folks want, but we don't tend to document misc
> performance improvements that have no API impact outside the kernel.

Yes, we should and do list such changes.  Also, 2.5% is quite good and it
is useful to collect such numbers in doc/CHANGES for marketing purposes.

> as for how much it helps, on a 12-CPU box " release" is about 2.5%
> faster.  if I enable __HAVE_CPU_UAREA_ROUTINES so that uareas are also
> accessed this way that gives an additional 0.5% speedup.

Cool!  Any reason why __HAVE_CPU_UAREA_ROUTINES is not enabled by default?

> coincidentally, this almost exactly compensates for the performance hit
> of enabling DIAGNOSTIC.

It really depends on the workload, e.g. effects on sysbench OLTP are quite
visible or e.g. PR/45734.

> -Chuck


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