Re: [PATCH]: R10000 Needs LL/SC Workaround in Glibc

[Kumba <kumba@gentoo.org>]

Ralf Baechle wrote:
> 
> In the kernel we have very good knowledge about what types of processors
> are being used for what configuration; much less in userland and the code
> as suggested by you would result in a silent failure on affected R10000
> machines if version built not for the R10000 was being used - iow no
> improvment over what we have right now.  So for userland I'd prefer to
> 
>  o MIPS I builds: use the some 28 nops.
>  o Builds for MIPS II or better: always use the branch likely
>  o A runtime test would have to be implemented pessimisticall because it
>    would have to rely on /proc being mounted which isn't available early in
>    the boot process.  It's probably going to add more overhead than it
>    saves anyway.
> 
> There is a price for using branch likely - but not that high.  In the grand
> picture it'll almost certainly vanish in the benchmarking noise.

Good idea.  I'll tinker with this once I wrap my head around the gcc-side of things.

-- 
Joshua Kinard
Gentoo/MIPS
kumba@gentoo.org

"The past tempts us, the present confuses us, the future frightens us.  And our 
lives slip away, moment by moment, lost in that vast, terrible in-between."

--Emperor Turhan, Centauri Republic