[PATCH] : libc_r/uthread/uthread_write.c

[Terry Lambert]

Daniel Eischen wrote:
> > > If you are using libkse or
> > > libthr, you will get a partial byte count and not zero because
> > > the tape driver returns the (partial) bytes written.  So exiting
> > > the loop in libc_r and returning 0 would only seem to correct
> > > the "problem" for libc_r.
> 
> If there is a difference, it could be because libc_r is using non-blocking
> IO behind the scenes, and sa(4) may be returning partial byte count
> in the non-blocking case and 0 (or -1 and ENOSPC) in the blocking case
> (which is what you'd get using libkse/libthr).

I would think that for non-block multiple and/or non-block-aligned
writes, there's no way to avoid the fault-in penalty for the need
to do read-before-write, so there will always be some unavoidable
stalls.

-- Terry