From patchwork Sat Oct 8 07:42:07 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Darrick J. Wong" X-Patchwork-Id: 118472 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id F2483B70FF for ; Sat, 8 Oct 2011 18:42:15 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752173Ab1JHHl6 (ORCPT ); Sat, 8 Oct 2011 03:41:58 -0400 Received: from e39.co.us.ibm.com ([32.97.110.160]:40243 "EHLO e39.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751343Ab1JHHl4 (ORCPT ); Sat, 8 Oct 2011 03:41:56 -0400 Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e39.co.us.ibm.com (8.14.4/8.13.1) with ESMTP id p987Q2L1007794; Sat, 8 Oct 2011 01:26:02 -0600 Received: from d03av03.boulder.ibm.com (d03av03.boulder.ibm.com [9.17.195.169]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p987fu6e170870; Sat, 8 Oct 2011 01:41:56 -0600 Received: from d03av03.boulder.ibm.com (loopback [127.0.0.1]) by d03av03.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p987fs7g027099; Sat, 8 Oct 2011 01:41:56 -0600 Received: from tux1.beaverton.ibm.com ([9.47.67.50]) by d03av03.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id p987fsof027092; Sat, 8 Oct 2011 01:41:54 -0600 Received: by tux1.beaverton.ibm.com (Postfix, from userid 501) id 216AA13E890; Sat, 8 Oct 2011 00:41:54 -0700 (PDT) Date: Sat, 8 Oct 2011 00:42:07 -0700 From: "Darrick J. Wong" To: Andreas Dilger , Herbert Xu , Theodore Tso , David Miller Cc: Joakim Tjernlund , Bob Pearson , linux-kernel , Mingming Cao , linux-crypto , linux-fsdevel , linux-ext4@vger.kernel.org Subject: [PATCH v5.1 4/4] crc32: Select an algorithm via kconfig Message-ID: <20111008074207.GK12447@tux1.beaverton.ibm.com> Reply-To: djwong@us.ibm.com References: <20111004235357.1560.12602.stgit@elm3c44.beaverton.ibm.com> <20111004235429.1560.89556.stgit@elm3c44.beaverton.ibm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20111004235429.1560.89556.stgit@elm3c44.beaverton.ibm.com> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org Oops, the description of CRC32_SLICEBY4 is a bit screwy. Let's try that again. --- Allow the kernel builder to choose a crc32* algorithm for the kernel. Signed-off-by: Darrick J. Wong --- lib/Kconfig | 36 ++++++++++++++++++++++++++++++++++++ lib/crc32defs.h | 18 ++++++++++++++++++ 2 files changed, 54 insertions(+), 0 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/lib/Kconfig b/lib/Kconfig index 477be04..27881d9 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -70,6 +70,42 @@ config CRC32_SELFTEST and crc32_be over byte strings with random alignment and length and computes the total elapsed time and number of bytes processed. +choice + prompt "CRC32 implementation" + depends on CRC32 + default CRC32_SLICEBY8 + +config CRC32_SLICEBY8 + bool "Slice by 8 bytes" + help + Calculate checksum 8 bytes at a time with a clever slicing algorithm. + This is the fastest algorithm, but comes with a 8KiB lookup table. + Most modern processors have enough cache that this shouldn't be + a problem. + + If you don't know which to choose, choose this one. + +config CRC32_SLICEBY4 + bool "Slice by 4 bytes" + help + Calculate checksum 4 bytes at a time with a clever slicing algorithm. + This is a bit slower than slice by 8, but has a smaller 4KiB lookup + table. + +config CRC32_SARWATE + bool "Sarwate's Algorithm (one byte at a time)" + help + Calculate checksum a byte at a time using Sarwate's algorithm. This + is not particularly fast, but has a small 256 byte lookup table. + +config CRC32_BIT + bool "Classic Algorithm (one bit at a time)" + help + Calculate checksum one bit at a time. This is VERY slow, but has + no lookup table. This is provided as a debugging option. + +endchoice + config CRC7 tristate "CRC7 functions" help diff --git a/lib/crc32defs.h b/lib/crc32defs.h index 6fd1917..64cba2c 100644 --- a/lib/crc32defs.h +++ b/lib/crc32defs.h @@ -13,6 +13,24 @@ */ #define CRC32C_POLY_LE 0x82F63B78 +/* Try to choose an implementation variant via Kconfig */ +#ifdef CONFIG_CRC32_SLICEBY8 +# define CRC_LE_BITS 64 +# define CRC_BE_BITS 64 +#endif +#ifdef CONFIG_CRC32_SLICEBY4 +# define CRC_LE_BITS 32 +# define CRC_BE_BITS 32 +#endif +#ifdef CONFIG_CRC32_SARWATE +# define CRC_LE_BITS 8 +# define CRC_BE_BITS 8 +#endif +#ifdef CONFIG_CRC32_BIT +# define CRC_LE_BITS 1 +# define CRC_BE_BITS 1 +#endif + /* * How many bits at a time to use. Valid values are 1, 2, 4, 8, 32 and 64. * For less performance-sensitive, use 4 or 8 to save table size.