- 31 Jul, 2012 1 commit
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Thiago Rafael Becker authored
Variables t4, t5, t6 and t7 are only used when CRC_LE_BITS != 32. Fix the following compilation warnings: lib/crc32.c: In function 'crc32_body': lib/crc32.c:77:55: warning: unused variable 't7' lib/crc32.c:77:41: warning: unused variable 't6' lib/crc32.c:77:27: warning: unused variable 't5' lib/crc32.c:77:13: warning: unused variable 't4' Signed-off-by:
Thiago Rafael Becker <trbecker@trbecker.org> Cc: "Darrick J. Wong" <djwong@us.ibm.com> Cc: Bob Pearson <rpearson@systemfabricworks.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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- 23 Mar, 2012 11 commits
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Darrick J. Wong authored
Add self-test code for crc32c. Signed-off-by:
Darrick J. Wong <djwong@us.ibm.com> Cc: Bob Pearson <rpearson@systemfabricworks.com> Signed-off-by:
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Darrick J. Wong authored
Reuse the existing crc32 code to stamp out a crc32c implementation. Signed-off-by:
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Bob Pearson authored
Add a comment at the top of crc32.c [djwong@us.ibm.com: Minor changelog tweaks] Signed-off-by:
Bob Pearson <rpearson@systemfabricworks.com> Signed-off-by:
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Bob Pearson authored
Add two changes that improve the performance of x86 systems 1. replace main loop with incrementing counter this change improves the performance of the selftest by about 5-6% on Nehalem CPUs. The apparent reason is that the compiler can use the loop index to perform an indexed memory access. This is reported to make the performance of PowerPC CPUs to get worse. 2. replace the rem_len loop with incrementing counter this change improves the performance of the selftest, which has more than the usual number of occurances, by about 1-2% on x86 CPUs. In actual work loads the length is most often a multiple of 4 bytes and this code does not get executed as often if at all. Again this change is reported to make the performance of PowerPC get worse. [djwong@us.ibm.com: Minor changelog tweaks] Signed-off-by:
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Bob Pearson authored
Add slicing-by-8 algorithm to the existing slicing-by-4 algorithm. This consists of: - extend largest BITS size from 32 to 64 - extend tables from tab[4][256] to up to tab[8][256] - Add code for inner loop. [djwong@us.ibm.com: Minor changelog tweaks] Signed-off-by:
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Bob Pearson authored
crc32.c provides a choice of one of several algorithms for computing the LSB and LSB versions of the CRC32 checksum based on the parameters CRC_LE_BITS and CRC_BE_BITS. In the original version the values 1, 2, 4 and 8 respectively selected versions of the alrogithm that computed the crc 1, 2, 4 and 32 bits as a time. This patch series adds a new version that computes the CRC 64 bits at a time. To make things easier to understand the parameter has been reinterpreted to actually stand for the number of bits processed in each step of the algorithm so that the old value 8 has been replaced with the value 32. This also allows us to add in a widely used crc algorithm that computes the crc 8 bits at a time called the Sarwate algorithm. [djwong@us.ibm.com: Minor changelog tweaks] Signed-off-by:
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Bob Pearson authored
crc32.c in its original version freely mixed u32, __le32 and __be32 types which caused warnings from sparse with __CHECK_ENDIAN__. This patch fixes these by forcing the types to u32. [djwong@us.ibm.com: Minor changelog tweaks] Signed-off-by:
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Bob Pearson authored
Misc cleanup of lib/crc32.c and related files. - remove unnecessary header files. - straighten out some convoluted ifdef's - rewrite some references to 2 dimensional arrays as 1 dimensional arrays to make them correct. I.e. replace tab[i] with tab[0][i]. - a few trivial whitespace changes - fix a warning in gen_crc32tables.c caused by a mismatch in the type of the pointer passed to output table. Since the table is only used at kernel compile time, it is simpler to make the table big enough to hold the largest column size used. One cannot make the column size smaller in output_table because it has to be used by both the le and be tables and they can have different column sizes. [djwong@us.ibm.com: Minor changelog tweaks] Signed-off-by:
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Bob Pearson authored
Replace the unit test provided in crc32.c, which doesn't have a makefile and doesn't compile with current headers, with a simpler self test routine that also gives a measure of performance and runs at module init time. The self test option can be enabled through a configuration option CONFIG_CRC32_SELFTEST. The test stresses the pre and post loops and is thus not very realistic since actual uses will likely have addresses and lengths that are at least 4 byte aligned. However, the main loop is long enough so that the performance is dominated by that loop. The expected values for crc32_le and crc32_be were generated with the original version of crc32.c using CRC_BITS_LE = 8 and CRC_BITS_BE = 8. These values were then used to check all the values of the BITS parameters in both the original and new versions. The performance results show some variability from run to run in spite of attempts to both warm the cache and reduce the amount of OS noise by limiting interrutps during the test. To get comparable results and to analyse options wrt performance the best time reported over a small sample of runs has been taken. [djwong@us.ibm.com: Minor changelog tweaks] Signed-off-by:
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Bob Pearson authored
Move a long comment from lib/crc32.c to Documentation/crc32.txt where it will more likely get read. Edited the resulting document to add an explanation of the slicing-by-n algorithm. [djwong@us.ibm.com: minor changelog tweaks] [akpm@linux-foundation.org: fix typo, per George] Signed-off-by:
George Spelvin <linux@horizon.com> Signed-off-by:
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Bob Pearson authored
This patchset (re)uses Bob Pearson's crc32 slice-by-8 code to stamp out a software crc32c implementation. It removes the crc32c implementation in crypto/ in favor of using the stamped-out one in lib/. There is also a change to Kconfig so that the kernel builder can pick an implementation best suited for the hardware. The motivation for this patchset is that I am working on adding full metadata checksumming to ext4. As far as performance impact of adding checksumming goes, I see nearly no change with a standard mail server ffsb simulation. On a test that involves only file creation and deletion and extent tree writes, I see a drop of about 50 pcercent with the current kernel crc32c implementation; this improves to a drop of about 20 percent with the enclosed crc32c code. When metadata is usually a small fraction of total IO, this new implementation doesn't help much because metadata is usually a small fraction of total IO. However, when we are doing IO that is almost all metadata (such as rm -rf'ing a tree), then this patch speeds up the operation substantially. Incidentally, given that iscsi, sctp, and btrfs also use crc32c, this patchset should improve their speed as well. I have not yet quantified that, however. This latest submission combines Bob's patches from late August 2011 with mine so that they can be one coherent patch set. Please excuse my inability to combine some of the patches; I've been advised to leave Bob's patches alone and build atop them instead. :/ Since the last posting, I've also collected some crc32c test results on a bunch of different x86/powerpc/sparc platforms. The results can be viewed here: http://goo.gl/sgt3i ; the "crc32-kern-le" and "crc32c" columns describe the performance of the kernel's current crc32 and crc32c software implementations. The "crc32c-by8-le" column shows crc32c performance with this patchset applied. I expect crc32 performance to be roughly the same. The two _boost columns at the right side of the spreadsheet shows how much faster the new implementation is over the old one. As you can see, crc32 rises substantially, and crc32c experiences a huge increase. This patch: - remove trailing whitespace from lib/crc32.c - remove trailing whitespace from lib/crc32defs.h [djwong@us.ibm.com: changelog tweaks] Signed-off-by:
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- 11 Jan, 2012 1 commit
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Joakim Tjernlund authored
Taking a pointer reference to each row in the crc table matrix, one can reduce the inner loop with a few insn's Signed-off-by:
Joakim Tjernlund <Joakim.Tjernlund@transmode.se> Cc: Bob Pearson <rpearson@systemfabricworks.com> Cc: Frank Zago <fzago@systemfabricworks.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by:
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- 26 Jul, 2011 1 commit
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Arun Sharma authored
This allows us to move duplicated code in <asm/atomic.h> (atomic_inc_not_zero() for now) to <linux/atomic.h> Signed-off-by:
Arun Sharma <asharma@fb.com> Reviewed-by:
Eric Dumazet <eric.dumazet@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Acked-by:
Mike Frysinger <vapier@gentoo.org> Signed-off-by:
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- 26 May, 2010 1 commit
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Andrew Morton authored
It doesn't work on big-endian - those architectures don't define __LITTLE_ENDIAN. Cc: Joakim Tjernlund <joakim.tjernlund@transmode.se> Reported-by:
Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by:
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- 25 May, 2010 2 commits
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Joakim Tjernlund authored
Since crc32.c contains a nifty test program that can be executed in user space, make sure endian detection works reliably in user space too. Signed-off-by:
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Joakim Tjernlund authored
Precompute more crc32 values(0xcc00, 0xcc0000 and 0xcc000000) into tables. This increases the table size from 1KB to 4KB but the performance benfit makes it worth it: 28% faster on MPC8321, 266 MHz 2x faster on Core 2 Duo, 3.1GHz [akpm@linux-foundation.org: coding-style fixes] Signed-off-by:
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- 30 Mar, 2010 1 commit
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Tejun Heo authored
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include bloc...
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- 06 Mar, 2010 1 commit
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Joakim Tjernlund authored
Signed-off-by:
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- 15 Dec, 2009 1 commit
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Joakim Tjernlund authored
Move common crc body to new function crc32_body() cleaup and micro optimize crc32_body for speed and less size. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by:
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- 03 Feb, 2008 1 commit
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Joe Perches authored
Signed-off-by:
Joe Perches <joe@perches.com> Signed-off-by:
Adrian Bunk <bunk@kernel.org>
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- 18 Oct, 2007 1 commit
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Ralf Baechle authored
To be consistent with the use of attributes in the rest of the kernel replace all use of __attribute_pure__ with __pure and delete the definition of __attribute_pure__. Signed-off-by:
Ralf Baechle <ralf@linux-mips.org> Cc: Russell King <rmk@arm.linux.org.uk> Acked-by:
Mauro Carvalho Chehab <mchehab@infradead.org> Cc: Bryan Wu <bryan.wu@analog.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by:
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- 08 Dec, 2006 1 commit
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Akinobu Mita authored
This patch replaces bitreverse() by bitrev32. The only users of bitreverse() are crc32 itself and via-velocity. Cc: Jeff Garzik <jgarzik@pobox.com> Cc: Matt Domsch <Matt_Domsch@dell.com> Signed-off-by:
Akinobu Mita <akinobu.mita@gmail.com> Signed-off-by:
Andrew Morton <akpm@osdl.org> Signed-off-by:
Linus Torvalds <torvalds@osdl.org>
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- 25 Jun, 2006 1 commit
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Randy Dunlap authored
Make kernel-doc corrections & additions to lib/crc*.c. Add crc functions to kernel-api.tmpl in DocBook. Signed-off-by:
Randy Dunlap <rdunlap@xenotime.net> Signed-off-by:
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- 07 Aug, 2005 1 commit
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Dominik Hackl authored
This patch fixes a typo in lib/crc32.c which results in incorrect debug output. Signed-off-by:
Dominik Hackl <dominik@hackl.dhs.org> Signed-off-by:
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- 16 Apr, 2005 1 commit
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Linus Torvalds authored
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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