IV31591: SLOWDOWN IN STD:SORT ON AIX

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APAR status

  • Closed as program error.

Error description

  • A significant performance degradation has been noticed in the
    std::sort routine on AIX when compared to other platforms.
    

Local fix

  • N/A
    

Problem summary

  • USERS AFFECTED:
    Users who use the sort in STL are potentially affected by this
    issue.
    PROBLEM DESCRIPTION:
    Sorting takes twice as much time than using other compilers
    when repeating every 100 values many times.
    The current sorting algorithm used in the XLC++ STL does not
    perform well with certain patterns, especially when there are a
    lot of repeated values.
    Changed the alogorithm to use a fat pivot rather than a single
    element as a pivot. This gives much better performance.
    

Problem conclusion

  • The current implementation of sorting is too simplistic and
    does not perform well.  It should be re-implemented with a more
    sophisticated algorithm.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IV31591

  • Reported component name

    XL C/C++ RUNTIM

  • Reported component ID

    5725C7201

  • Reported release

    C10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-11-07

  • Closed date

    2012-11-07

  • Last modified date

    2012-11-07

  • APAR is sysrouted FROM one or more of the following:

  • APAR is sysrouted TO one or more of the following:

Fix information

  • Fixed component name

    XL C/C++ RUNTIM

  • Fixed component ID

    5725C7201

Applicable component levels

  • RC10 PSY U856069

       UP C



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Document information


More support for:

XL C/C++ for AIX
C/C++ Runtime

Software version:

12.1

Reference #:

IV31591

Modified date:

2012-11-07

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