Author: jilles
Date: Thu May 18 22:10:04 2017
New Revision: 318502
URL: https://svnweb.freebsd.org/changeset/base/318502
Log:
sh: Keep output buffer across builtins.
Allocating and deallocating repeatedly the 1024-byte buffer for stdout from
builtins costs CPU time for little or no benefit.
A simple loop containing builtins that write to a file descriptor, such as
i=0; while [ "$i" -lt 1000000 ]; do printf .; i=$((i+1)); done >/dev/null
is over 10% faster in a simple benchmark on an amd64 virtual machine.
Modified:
head/bin/sh/output.c
Modified: head/bin/sh/output.c
==============================================================================
--- head/bin/sh/output.c Thu May 18 21:44:14 2017 (r318501)
+++ head/bin/sh/output.c Thu May 18 22:10:04 2017 (r318502)
@@ -254,14 +254,7 @@ flushout(struct output *dest)
void
freestdout(void)
{
- INTOFF;
- if (output.buf) {
- ckfree(output.buf);
- output.nextc = NULL;
- output.buf = NULL;
- output.bufend = NULL;
- }
- INTON;
+ output.nextc = output.buf;
}
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