Module Name:	syssrc
Committed By:	jdolecek
Date:		Mon Jul  2 20:43:41 UTC 2001

Modified Files:
	syssrc/sys/kern: sys_pipe.c

Log Message:
Don't try to be too smart about chunking - if the data size is bigger
than PIPE_CHUNK_SIZE, just transfer first PIPE_CHUNK_SIZE and return short
write, expecting the caller to call us again later (if they need). Previous
behaviour (besides being wrong for O_NONBLOCK reads) hung hbench under some
circumstances and other applications may have similar expectations as hbench.
This might also fix port-vax/13333 by Manuel Bowyer.

Other changes to pipe_direct_write() include:
* return short write (and success) on EOF if any data were already read;
  we return EPIPE on next write(2) call
* simplify error handling, actually handle uvm_loan() failure correctly,
  call pipe_loan_free() on error explicitly and only call uvm_unloan()
  if the address space was _not_ already freed by pipe_loan_free()
  Thanks Chuck Silvers for uvm_unloan() hints :)

Fallthough to common write in pipe_write() if pipe_direct_write()
returns ENOMEM, otherwise always break out immediatelly.
Use uvm_km_valloc_wait() instead uvm_km_valloc() in pipe_loan_alloc().


To generate a diff of this commit:
cvs rdiff -r1.4 -r1.5 syssrc/sys/kern/sys_pipe.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.