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    Subject[PATCH 0/2] New jhash function

    Please consider applying the following patch:

    The current jhash.h implements the lookup2() hash function by Bob Jenkins.
    However, lookup2() is outdated as Bob wrote a new hash function called
    lookup3(). The new hash function

    - mixes better than lookup2(): it passes the check that every input bit
    changes every output bit 50% of the time, while lookup2() failed it.
    - performs better: compiled with -O2 on Core2 Duo, lookup3() 20-40% faster
    than lookup2() depending on the key length.

    You can read a longer comparison of the two and other hash functions at

    jhash is widely used in the kernel and because the functions
    are inlined, the cost in size is significant. The new functions
    are slightly larger than the previous ones so the new implementation
    uses non-inlined fucntions. (See
    Therefore the first patch replaces the calls to the internal macros
    of jhash with the jhash function calls and the second patch contains
    the implementation of the new jhash functions.

    Jozsef Kadlecsik (2):
    Prepare the tree for un-inlined jhash.
    The new jhash implementation

    include/linux/jhash.h | 136 ++-------------------------------
    lib/Makefile | 2 +-
    lib/jhash.c | 153 ++++++++++++++++++++++++++++++++++++++
    net/ipv6/inet6_connection_sock.c | 18 ++---
    net/ipv6/reassembly.c | 36 ++++-----
    5 files changed, 186 insertions(+), 159 deletions(-)
    create mode 100644 lib/jhash.c

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      Last update: 2010-11-25 14:25    [W:0.019 / U:6.316 seconds]
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