Introduce FEATURE_COPYBUF_KB.

People who want smaller stack at any cost may use it
to reduce cp's stack usage (FEATURE_COPYBUF_KB=1).
Desktop people may get faster copy of big files
(FEATURE_COPYBUF_KB=32 is ~30% faster than 4kb)

1 files changed, 10 insertions, 0 deletions

diff --git a/libbb/Config.in b/libbb/Config.in
index 5055015cf..6bbeffb43 100644
--- a/libbb/Config.in
+++ b/libbb/Config.in
@@ -110,6 +110,16 @@ config FEATURE_EDITING_FANCY_PROMPT
           Setting this option allows for prompts to use things like \w and
           \$ and escape codes.
 
+config FEATURE_COPYBUF_KB
+        int "Copy buffer size, in kilobytes"
+        range 1 1024
+        default 4
+        help
+          Size of buffer used by cp, mv, install etc.
+          Buffers which are 4 kb or less will be allocated on stack.
+          Bigger buffers will be allocated with mmap, with fallback to 4 kb
+          stack buffer if mmap fails.
+
 config MONOTONIC_SYSCALL
         bool "Use clock_gettime(CLOCK_MONOTONIC) syscall"
         default y