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IV58939: EFFECT POOLBUCKETS CHANGES FROM 2 TO 7 AND AT BOOT APPLIES TO AIX 7100-03

A fix is available

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APAR status

  • Closed as program error.

Error description

  • The out-of-the box value for poolbuckets differs between
    P7 and P8.  This ends up in 3 extra locks/unlocks
    during mbuf Get/Alloc on P8 compared to P7, which
    for some workloads may result in a net penalty.
    Additionally, the poolbuckets network option is not effective
    between values of 2 and 7, or at boot time.  The tunable
    therefore cannot be used on P8 to reduce the number of
    buckets to the P7 value.
    

Local fix

Problem summary

  • The out-of-the box value for poolbuckets differs between
    P7 and P8.  This ends up in 3 extra locks/unlocks
    during mbuf Get/Alloc on P8 compared to P7, which
    for some workloads may result in a net penalty.
    Additionally, the poolbuckets network option is not effective
    between values of 2 and 7, or at boot time.  The tunable
    therefore cannot be used on P8 to reduce the number of
    buckets to the P7 value.
    

Problem conclusion

  • In the original code, when the "poolbuckets" value was less
    than 7, it would pick the minimum of POOLBUCKETSMAX (7) or
    _system_configuration.smt_threads (which defaults to 4 in P7
    systems and 8 in P8 systems).  The solution retains the
    above behavior for the default case (poolbuckets=1). For all
    other cases it allows the user's choice to take effect. It
    also makes the changes effective at boot time from the next
    reboot, so that the UDP code which uses the value at boot time
    can also pick up the tuned value.
    

Temporary fix

Comments

  • 7100-03 - use AIX APAR IV58939
    7100-04 - use AIX APAR IV58875
    

APAR Information

  • APAR number

    IV58939

  • Reported component name

    AIX V7.1

  • Reported component ID

    5765H4000

  • Reported release

    710

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Submitted date

    2014-04-08

  • Closed date

    2014-04-08

  • Last modified date

    2016-05-10

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

    IV58875

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

    U866419

Fix information

  • Fixed component name

    AIX V7.1

  • Fixed component ID

    5765H4000

Applicable component levels

  • R710 PSY U866419

       UP14/05/22 I 1000



Document information

More support for: AIX Enterprise Edition

Software version: 710

Operating system(s): AIX

Reference #: IV58939

Modified date: 10 May 2016