Filtering calls based on return value

[Grant Edwards]

After sifting through 24MB of strace output showing read() returning
EAGAIN to find the 4KB of useful stuff, I was going to try add an
option to strace to do that (ignore calls to read/write/send/recv that
return EAGAIN).  I had forgotten that the output is produced in two
stages: part of it on entry and part of it on exit.

It looks like filtering out calls based on the return value isn't
very practical -- am I wrong?

-- 
Grant