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From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
 Paul Mackerras <paulus@samba.org>
Subject: [PATCH v2] powerpc 8xx: defconfig: slice by 4 is more efficient than
 the default slice by 8 on Powerpc 8xx.
Message-Id: <20131122172829.CC8EE1A4DE7@localhost.localdomain>
Date: Fri, 22 Nov 2013 18:28:29 +0100 (CET)
Cc: scottwood@freescale.com, linuxppc-dev@lists.ozlabs.org,
 linux-kernel@vger.kernel.org
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On PPC_8xx, CRC32_SLICEBY4 is more efficient (almost twice) than CRC32_SLICEBY8,
as shown below:

With CRC32_SLICEBY8:
[    1.109204] crc32: CRC_LE_BITS = 64, CRC_BE BITS = 64
[    1.114401] crc32: self tests passed, processed 225944 bytes in 15118910 nsec
[    1.130655] crc32c: CRC_LE_BITS = 64
[    1.134235] crc32c: self tests passed, processed 225944 bytes in 4479879 nsec

With CRC32_SLICEBY4:
[    1.097129] crc32: CRC_LE_BITS = 32, CRC_BE BITS = 32
[    1.101878] crc32: self tests passed, processed 225944 bytes in 8616242 nsec
[    1.116298] crc32c: CRC_LE_BITS = 32
[    1.119607] crc32c: self tests passed, processed 225944 bytes in 3289576 nsec

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>

diff -ur a/arch/powerpc/configs/adder875_defconfig b/arch/powerpc/configs.new/adder875_defconfig
--- a/arch/powerpc/configs/adder875_defconfig	2013-11-22 18:20:10.342968268 +0100
+++ b/arch/powerpc/configs.new/adder875_defconfig	2013-11-22 18:17:46.499686457 +0100
@@ -70,3 +70,4 @@
 CONFIG_DETECT_HUNG_TASK=y
 CONFIG_DEBUG_INFO=y
 # CONFIG_RCU_CPU_STALL_DETECTOR is not set
+CONFIG_CRC32_SLICEBY4=y
diff -ur a/arch/powerpc/configs/ep88xc_defconfig b/arch/powerpc/configs.new/ep88xc_defconfig
--- a/arch/powerpc/configs/ep88xc_defconfig	2013-11-22 18:20:10.286961148 +0100
+++ b/arch/powerpc/configs.new/ep88xc_defconfig	2013-11-22 18:17:41.992113565 +0100
@@ -72,3 +72,4 @@
 CONFIG_DETECT_HUNG_TASK=y
 CONFIG_DEBUG_INFO=y
 # CONFIG_RCU_CPU_STALL_DETECTOR is not set
+CONFIG_CRC32_SLICEBY4=y
diff -ur a/arch/powerpc/configs/mpc866_ads_defconfig b/arch/powerpc/configs.new/mpc866_ads_defconfig
--- a/arch/powerpc/configs/mpc866_ads_defconfig	2013-11-22 18:20:10.323965853 +0100
+++ b/arch/powerpc/configs.new/mpc866_ads_defconfig	2013-11-22 18:17:32.480904735 +0100
@@ -55,3 +55,4 @@
 CONFIG_CRC_CCITT=y
 # CONFIG_RCU_CPU_STALL_DETECTOR is not set
 # CONFIG_CRYPTO_ANSI_CPRNG is not set
+CONFIG_CRC32_SLICEBY4=y
diff -ur a/arch/powerpc/configs/mpc885_ads_defconfig b/arch/powerpc/configs.new/mpc885_ads_defconfig
--- a/arch/powerpc/configs/mpc885_ads_defconfig	2013-11-22 18:20:10.326966235 +0100
+++ b/arch/powerpc/configs.new/mpc885_ads_defconfig	2013-11-22 18:17:25.760050546 +0100
@@ -78,3 +78,4 @@
 CONFIG_DETECT_HUNG_TASK=y
 CONFIG_DEBUG_INFO=y
 # CONFIG_RCU_CPU_STALL_DETECTOR is not set
+CONFIG_CRC32_SLICEBY4=y
diff -ur a/arch/powerpc/configs/tqm8xx_defconfig b/arch/powerpc/configs.new/tqm8xx_defconfig
--- a/arch/powerpc/configs/tqm8xx_defconfig	2013-11-22 18:20:10.317965090 +0100
+++ b/arch/powerpc/configs.new/tqm8xx_defconfig	2013-11-22 18:17:14.926673681 +0100
@@ -84,3 +84,4 @@
 CONFIG_DETECT_HUNG_TASK=y
 CONFIG_DEBUG_INFO=y
 # CONFIG_RCU_CPU_STALL_DETECTOR is not set
+CONFIG_CRC32_SLICEBY4=y