Mesa (master): util: use faster zlib's CRC32 implementaion
Grazvydas Ignotas
notaz at kemper.freedesktop.org
Sun Jan 14 17:11:47 UTC 2018
Module: Mesa
Branch: master
Commit: 6acf22a17991e3e98c35596f0b1cedfaebed6ec3
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=6acf22a17991e3e98c35596f0b1cedfaebed6ec3
Author: Grazvydas Ignotas <notasas at gmail.com>
Date: Fri Dec 29 02:05:05 2017 +0200
util: use faster zlib's CRC32 implementaion
zlib provides a faster slice-by-4 CRC32 implementation than the
traditional single byte lookup one used by mesa. As most supported
platforms now link zlib unconditionally, we can easily use it.
Improvement for a 1MB buffer (avg MB/s, n=100, zlib 1.2.8):
i5-6600K C2D E4500
mesa zlib mesa zlib
443 1443 225% +/- 2.1% 403 1175 191% +/- 0.9%
It has been verified the calculation results stay the same after this
change.
Signed-off-by: Grazvydas Ignotas <notasas at gmail.com>
Reviewed-by: Eric Engestrom <eric.engestrom at imgtec.com>
Reviewed-by: Marek Olšák <marek.olsak at amd.com>
Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>
---
src/util/crc32.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/src/util/crc32.c b/src/util/crc32.c
index f2e01c61e5..425046ab5f 100644
--- a/src/util/crc32.c
+++ b/src/util/crc32.c
@@ -33,6 +33,9 @@
*/
+#ifdef HAVE_ZLIB
+#include <zlib.h>
+#endif
#include "crc32.h"
@@ -114,6 +117,16 @@ util_hash_crc32(const void *data, size_t size)
const uint8_t *p = data;
uint32_t crc = 0xffffffff;
+#ifdef HAVE_ZLIB
+ /* Prefer zlib's implementation for better performance.
+ * zlib's uInt is always "unsigned int" while size_t can be 64bit.
+ * Since 1.2.9 there's crc32_z that takes size_t, but use the more
+ * available function to avoid build system complications.
+ */
+ if ((uInt)size == size)
+ return ~crc32(0, data, size);
+#endif
+
while (size--)
crc = util_crc32_table[(crc ^ *p++) & 0xff] ^ (crc >> 8);
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