svn commit: r335072 - head/sys/amd64/amd64

[Rodney W. Grimes]

> Author: kib
> Date: Wed Jun 13 17:55:09 2018
> New Revision: 335072
> URL: https://svnweb.freebsd.org/changeset/base/335072
> 
> Log:
>   Enable eager FPU context switch by default on amd64.
>   
>   With compilers making increasing use of vector instructions the
>   performance benefit of lazily switching FPU state is no longer a
>   desirable tradeoff.  Linux switched to eager FPU context switch some
>   time ago, and the idea was floated on the FreeBSD-current mailing list
>   some years ago[1].
>   
>   Enable eager FPU context switch by default on amd64, with a tunable/sysctl
>   available to turn it back off.
>   
>   [1] https://lists.freebsd.org/pipermail/freebsd-current/2015-March/055198.html
>   
>   Reviewed by:	jhb
>   Tested by:	pho
>   Sponsored by:	The FreeBSD Foundation

MFC: ?

...

-- 
Rod Grimes                                                 rgrimes at freebsd.org