The branch stable/13 has been updated by pfg:
URL:
https://cgit.FreeBSD.org/src/commit/?id=62d555c4e82852bf80b1d833a31ff4dc7833f4cd
commit 62d555c4e82852bf80b1d833a31ff4dc7833f4cd
Author: Pedro F. Giffuni <p...@freebsd.org>
AuthorDate: 2021-05-31 01:48:38 +0000
Commit: Pedro F. Giffuni <p...@freebsd.org>
CommitDate: 2021-06-15 21:26:31 +0000
fread: improve performance for unbuffered reads
We can use the buffer passed to fread(3) directly in the FILE *.
The buffer needs to be reset before each call to __srefill().
This preserves the expected behavior in all cases.
The change was found originally in OpenBSD and later adopted by NetBSD.
MFC after: 2 weeks
Obtained from: OpenBSD (CVS 1.18)
Differential Revision: https://reviews.freebsd.org/D30548
---
lib/libc/stdio/fread.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/lib/libc/stdio/fread.c b/lib/libc/stdio/fread.c
index c12bcf1148b7..11f8d13f0caf 100644
--- a/lib/libc/stdio/fread.c
+++ b/lib/libc/stdio/fread.c
@@ -99,6 +99,35 @@ __fread(void * __restrict buf, size_t size, size_t count,
FILE * __restrict fp)
fp->_r = 0;
total = resid;
p = buf;
+
+ /*
+ * If we're unbuffered we know that the buffer in fp is empty so
+ * we can read directly into buf. This is much faster than a
+ * series of one byte reads into fp->_nbuf.
+ */
+ if ((fp->_flags & __SNBF) != 0 && buf != NULL) {
+ while (resid > 0) {
+ /* set up the buffer */
+ fp->_bf._base = fp->_p = p;
+ fp->_bf._size = resid;
+
+ if (__srefill(fp)) {
+ /* no more input: return partial result */
+ count = (total - resid) / size;
+ break;
+ }
+ p += fp->_r;
+ resid -= fp->_r;
+ }
+
+ /* restore the old buffer (see __smakebuf) */
+ fp->_bf._base = fp->_p = fp->_nbuf;
+ fp->_bf._size = 1;
+ fp->_r = 0;
+
+ return (count);
+ }
+
while (resid > (r = fp->_r)) {
(void)memcpy((void *)p, (void *)fp->_p, (size_t)r);
fp->_p += r;
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