[MPlayer-users] Gcc 3.4.2 soft-float + uclibc performance question?

[Alexander Roalter]

YongLi wrote:
> Hello All,
> 
> I am portting the mplayer to ARM CPU using ARM gcc 3.4.2 soft-float + uclibc as the toolchain(built using buildroot).
> 
> However, the mplayer performace decrases! 
> 
> I have performed some float tests, the soft-float uclibc is faster than glibc hard float when computing sin float div/mult functions. 
> 
> Why the mplayer performance decreases?
> 
> Thanks !
To my knowledge there is no hard float on ARM cpus (without the VFP 
coprocessor, which I have not encountered yet). Heck, even division has 
to be done software-wise. So there could only be a distinction whether 
the replacement routines for glibc hard float are less efficient than 
the soft float ones. I assume usage of hard float creates an exception 
(coprocessor not found) which has then to be re-routed to the soft-float 
backup, with at least two more process switches (user-space -> exception 
(Illegal Instruction) -> kernel code exception handling ...)

hth,
Alex