[EE] Saving "printf" arguments for later? Real-time on slow processor.

I've got a situation where I am running a very slow processor that happens
to have a lot of spare RAM. The CPU sits idle half of the time. It has some
real time processing that it must do on time every handful of seconds. It
is just barely fast enough to do its real time work without printfs.

The device firmware interfaces with a huge complicated third party library.
This library implements a "debug mode" where it calls printf in various
places.

In debug mode it easily generates several kilobytes of formatted number
containing text per minute. And, what the library does is so complicated
that we really need the debug output to be generated all of the time (both
in development and production).

Unfortunately, It turns out that printf is so slow that it causes the
system to fail in a variety of subtle yet completely catastrophic ways.
(due to it missing real time deadlines and not being able to detect that it
has missed them)

Has anyone dealt with this before?

I've reached the conclusion that my best bet is to write a wrapper for
printf.
The wrapper would save the printf format string, and variadic arguments to
a buffer so that I can process the printfs later when the CPU is idle.
I think I can get away with this since all of the printfs just contain
numbers and short (~8 byte) strings.

I'd be interested to hear other people's thoughts and experiences with this
sort of problem.


-- 
Jason White