1. 23 Mar, 2012 2 commits
    • Bob Pearson's avatar
      crc32: move long comment about crc32 fundamentals to Documentation/ · fbedceb1
      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: default avatarGeorge Spelvin <linux@horizon.com>
      Signed-off-by: default avatarBob Pearson <rpearson@systemfabricworks.com>
      Signed-off-by: default avatarDarrick J. Wong <djwong@us.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      fbedceb1
    • Bob Pearson's avatar
      crc32: remove two instances of trailing whitespaces · e30c7a8f
      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: default avatarBob Pearson <rpearson@systemfabricworks.com>
      Signed-off-by: default avatarDarrick J. Wong <djwong@us.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e30c7a8f
  2. 11 Jan, 2012 1 commit
  3. 26 Jul, 2011 1 commit
  4. 26 May, 2010 1 commit
  5. 25 May, 2010 2 commits
  6. 30 Mar, 2010 1 commit
    • Tejun Heo's avatar
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking... · 5a0e3ad6
      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
        blocks and try to put the new include such that its order conforms
        to its surrounding.  It's put in the include block which contains
        core kernel includes, in the same order that the rest are ordered -
        alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
        doesn't seem to be any matching order.
      
      * If the script can't find a place to put a new include (mostly
        because the file doesn't have fitting include block), it prints out
        an error message indicating which .h file needs to be added to the
        file.
      
      The conversion was done in the following steps.
      
      1. The initial automatic conversion of all .c files updated slightly
         over 4000 files, deleting around 700 includes and adding ~480 gfp.h
         and ~3000 slab.h inclusions.  The script emitted errors for ~400
         files.
      
      2. Each error was manually checked.  Some didn't need the inclusion,
         some needed manual addition while adding it to implementation .h or
         embedding .c file was more appropriate for others.  This step added
         inclusions to around 150 files.
      
      3. The script was run again and the output was compared to the edits
         from #2 to make sure no file was left behind.
      
      4. Several build tests were done and a couple of problems were fixed.
         e.g. lib/decompress_*.c used malloc/free() wrappers around slab
         APIs requiring slab.h to be added manually.
      
      5. The script was run on all .h files but without automatically
         editing them as sprinkling gfp.h and slab.h inclusions around .h
         files could easily lead to inclusion dependency hell.  Most gfp.h
         inclusion directives were ignored as stuff from gfp.h was usually
         wildly available and often used in preprocessor macros.  Each
         slab.h inclusion directive was examined and added manually as
         necessary.
      
      6. percpu.h was updated not to include slab.h.
      
      7. Build test were done on the following configurations and failures
         were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
         distributed build env didn't work with gcov compiles) and a few
         more options had to be turned off depending on archs to make things
         build (like ipr on powerpc/64 which failed due to missing writeq).
      
         * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
         * powerpc and powerpc64 SMP allmodconfig
         * sparc and sparc64 SMP allmodconfig
         * ia64 SMP allmodconfig
         * s390 SMP allmodconfig
         * alpha SMP allmodconfig
         * um on x86_64 SMP allmodconfig
      
      8. percpu.h modifications were reverted so that it could be applied as
         a separate patch and serve as bisection point.
      
      Given the fact that I had only a couple of failures from tests on step
      6, I'm fairly confident about the coverage of this conversion patch.
      If there is a breakage, it's likely to be something in one of the arch
      headers which should be easily discoverable easily on most builds of
      the specific arch.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Guess-its-ok-by: default avatarChristoph Lameter <cl@linux-foundation.org>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
      5a0e3ad6
  7. 06 Mar, 2010 1 commit
  8. 15 Dec, 2009 1 commit
  9. 03 Feb, 2008 1 commit
  10. 18 Oct, 2007 1 commit
  11. 08 Dec, 2006 1 commit
  12. 25 Jun, 2006 1 commit
  13. 07 Aug, 2005 1 commit
  14. 16 Apr, 2005 1 commit
    • Linus Torvalds's avatar
      Linux-2.6.12-rc2 · 1da177e4
      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!
      1da177e4