From: "Darrick J. Wong" <djwong@us.ibm.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Theodore Tso <tytso@mit.edu>,
Joakim Tjernlund <joakim.tjernlund@transmode.se>,
Bob Pearson <rpearson@systemfabricworks.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Andreas Dilger <adilger.kernel@dilger.ca>,
linux-crypto <linux-crypto@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Mingming Cao <cmm@us.ibm.com>,
linux-ext4@vger.kernel.org,
Herbert Xu <herbert@gondor.apana.org.au>
Subject: [PATCH 04/14] crc32: Speed up memory table access on powerpc
Date: Thu, 01 Dec 2011 12:14:10 -0800 [thread overview]
Message-ID: <20111201201410.5876.17840.stgit@elm3c44.beaverton.ibm.com> (raw)
In-Reply-To: <20111201201341.5876.83743.stgit@elm3c44.beaverton.ibm.com>
Replace 2D array references by pointer references in loops.
This change has no effect on X86 code but improves PPC
performance.
From: Bob Pearson <rpearson@systemfabricworks.com>
Signed-off-by: Bob Pearson <rpearson@systemfabricworks.com>
[djwong@us.ibm.com: Minor changelog tweaks]
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
---
lib/crc32.c | 21 +++++++++++----------
1 files changed, 11 insertions(+), 10 deletions(-)
diff --git a/lib/crc32.c b/lib/crc32.c
index 7a0e5a9..c93c9ae 100644
--- a/lib/crc32.c
+++ b/lib/crc32.c
@@ -53,20 +53,21 @@ static inline u32
crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256])
{
# ifdef __LITTLE_ENDIAN
-# define DO_CRC(x) crc = tab[0][(crc ^ (x)) & 255] ^ (crc >> 8)
-# define DO_CRC4 crc = tab[3][(crc) & 255] ^ \
- tab[2][(crc >> 8) & 255] ^ \
- tab[1][(crc >> 16) & 255] ^ \
- tab[0][(crc >> 24) & 255]
+# define DO_CRC(x) (crc = t0[(crc ^ (x)) & 255] ^ (crc >> 8))
+# define DO_CRC4 crc = t3[(crc) & 255] ^ \
+ t2[(crc >> 8) & 255] ^ \
+ t1[(crc >> 16) & 255] ^ \
+ t0[(crc >> 24) & 255]
# else
-# define DO_CRC(x) crc = tab[0][((crc >> 24) ^ (x)) & 255] ^ (crc << 8)
-# define DO_CRC4 crc = tab[0][(crc) & 255] ^ \
- tab[1][(crc >> 8) & 255] ^ \
- tab[2][(crc >> 16) & 255] ^ \
- tab[3][(crc >> 24) & 255]
+# define DO_CRC(x) (crc = t0[((crc >> 24) ^ (x)) & 255] ^ (crc << 8))
+# define DO_CRC4 crc = t0[(crc) & 255] ^ \
+ t1[(crc >> 8) & 255] ^ \
+ t2[(crc >> 16) & 255] ^ \
+ t3[(crc >> 24) & 255]
# endif
const u32 *b;
size_t rem_len;
+ const u32 *t0 = tab[0], *t1 = tab[1], *t2 = tab[2], *t3 = tab[3];
/* Align it */
if (unlikely((long)buf & 3 && len)) {
next prev parent reply other threads:[~2011-12-01 20:14 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-01 20:13 [PATCH v5.2 00/14] crc32c: Add faster algorithm and self-test code Darrick J. Wong
2011-12-01 20:13 ` [PATCH 01/14] crc32: removed two instances of trailing whitespaces Darrick J. Wong
2011-12-01 20:13 ` [PATCH 02/14] crc32: Move long comment about crc32 fundamentals to Documentation/ Darrick J. Wong
2011-12-01 20:14 ` [PATCH 03/14] crc32: Simplify unit test code Darrick J. Wong
2011-12-01 20:14 ` Darrick J. Wong [this message]
2011-12-01 20:14 ` [PATCH 05/14] crc32: Miscellaneous cleanups Darrick J. Wong
2011-12-01 20:14 ` [PATCH 06/14] crc32: Fix mixing of endian-specific types Darrick J. Wong
2011-12-01 20:14 ` [PATCH 07/14] crc32: Make CRC_*_BITS definition correspond to actual bit counts Darrick J. Wong
2011-12-01 20:14 ` [PATCH 08/14] crc32: Add slice-by-8 algorithm to existing code Darrick J. Wong
2011-12-01 20:14 ` [PATCH 09/14] crc32: Optimize loop counter for x86 Darrick J. Wong
2011-12-01 20:14 ` [PATCH 10/14] crc32: Add note about this patchset to crc32.c Darrick J. Wong
2011-12-01 20:14 ` [PATCH 11/14] crc32: Bolt on crc32c Darrick J. Wong
2011-12-01 20:15 ` [PATCH 12/14] crypto: crc32c should use library implementation Darrick J. Wong
2011-12-01 20:15 ` [PATCH 13/14] crc32: Add self-test code for crc32c Darrick J. Wong
2011-12-01 20:15 ` [PATCH 14/14] crc32: Select an algorithm via kconfig Darrick J. Wong
2011-12-02 0:25 ` Herbert Xu
2011-12-03 2:36 ` Darrick J. Wong
2011-12-12 22:58 ` Darrick J. Wong
2011-12-12 23:10 ` Bob Pearson
2011-12-13 6:32 ` Darrick J. Wong
2011-12-13 8:27 ` Joakim Tjernlund
2011-12-13 18:36 ` Darrick J. Wong
2011-12-01 20:20 ` [PATCH v5.2 00/14] crc32c: Add faster algorithm and self-test code Joel Becker
2011-12-01 20:31 ` Darrick J. Wong
2011-12-02 0:23 ` Herbert Xu
2011-12-03 2:30 ` Darrick J. Wong
2011-12-03 11:00 ` Herbert Xu
2012-01-07 5:50 [PATCH v5.3 " Darrick J. Wong
2012-01-07 5:51 ` [PATCH 04/14] crc32: Speed up memory table access on powerpc Darrick J. Wong
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