svn commit: r268566 - head/usr.bin/users

[Joerg Sonnenberger]

On Mon, Jul 14, 2014 at 08:37:56PM +0100, Alexander Nasonov wrote:
> Joerg Sonnenberger wrote:
> > On Sat, Jul 12, 2014 at 09:34:28PM +1000, Bruce Evans wrote:
> > > Run time:
> > > C++ sort() was twice as slow as qsort() for sorting 1 million dummy
> > > users in the allocation tests.  About 8 seconds instead of 4, except
> > > when compiled with -g -O0 it was 15 seconds instead of 4.
> > 
> > I find that claim strange and not reproducable. In my tests, std::sort
> > tends to be significant faster than qsort. Attached is a small test
> > program that for me is twice as fast for sorting integers...
> 
> Integers are faster indeed but I'm not sure about used-defined
> types like basic_string<CharT,TraitsT,AllocT>. qsort uses 3-way
> comparison while std::sort always uses less_than (a<b) and !(a<b).
> The compiler can optimize when a and b are integers but not when
> they're user-defined types with a user-defined comparison function.

The trinary vs binary partial order function only matters if you have
lots of duplicate values.

Joerg