Re: musl for ARM

[Rich Felker <dalias@aerifal.cx>]

On Wed, Oct 03, 2012 at 12:18:59AM +0800, Brian Wang wrote:
> > One area you can get vastly better performance with musl is
> > application startup overhead. Especially with static linking, but even
> > with dynamic linking if your only .so is libc, the startup time is
> > 2-5x faster than glibc, which really makes a difference to the runtime
> > of shell scripts (like configure) that invoke tons of external
> > programs.
> 
> ok.  that makes sense.  the faster application startup time is one of the
> performance figure that i'm looking for.

For individual applications, the difference is not going to be
perceptible unless you're comparing static-linked musl to
dynamic-linked glibc, on apps that use a ton of libraries. In that
case, static-linked glibc would also be fairly fast at startup, but
setting up glibc for static linking is rather difficult.

The place you'll see a real noticable difference is when starting
thousands of tiny, short-lived programs -- this happens mostly in
configure scripts and bloated init-scripts.

If boot time is an issue, musl (especially with static linking) could
help a lot. Combining that with a more streamlined initscript setup
could make even more of a difference.

> i built the musl toolchain with the musl cross project found on the musl
> community wiki.  i did replace the 3.x kernel with my oldish 2.6.24.  any
> pointers on how to sanitize kernel headers?  i have not built toolchains
> myself since the days when prebuilt toolchains were readily available...

I would be careful with older kernels. There have been important fixes
as late as 2.6.27 or 2.6.31 (I forget exactly...somewhere around
there) and you should at least be aware of the issues and backport
security fixes if using older kernels.

Rich