cat: use larger buffer sizes to reduce read/write-syscall overhead

* src/cat.c (max): Remove definition.  Use MAX from system.h instead.
(compute_buffer_size): New function to compute the input and output
buffer sizes, which are now set at 8 times st_blksize with a maximum
of 32KiB. Previously the typical block sizes used were 1KiB for pipes
and 4KiB for files, and now will be 8KiB and 32KiB respectively.
(main): Use it.
This change can double throughput on modern systems.  For timings,
see http://article.gmane.org/gmane.comp.gnu.core-utils.bugs/16040
Suggestion from Tzvi Rotshtein.

1 files changed, 1 insertions, 0 deletions

diff --git a/THANKS b/THANKS
index e8c7b5cd1..c4e900b12 100644
--- a/THANKS
+++ b/THANKS
@@ -553,6 +553,7 @@ Torbjorn Granlund                   tege@nada.kth.se
 Torbjorn Lindgren                   tl@funcom.no
 Torsten Landschoff                  torsten@pclab.ifg.uni-kiel.de
 Tristan Miller                      psychonaut@nothingisreal.com
+Tzvi Rotshtein                      tzvi.ro@gmail.com
 Ulrich Drepper                      drepper@gnu.org
 Ulrich Hermisson                    ulrich_hermisson@hotmail.com
 Urs Thuermann                       urs@isnogud.escape.de