IBM Support

IV51764: HIGH CPU DUE TO EXCESSIVE JIT ACTIVITY

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APAR status

  • Closed as program error.

Error description

  • Error Message: Under some circumstances a JIT code cache can get
stuck in the reserved state, causing the JIT compiler to waste
CPU cycles when the code cache is full and no useful compilation
is possible. The problem can be confirmed by taking a JIT
verbose log which will show many failed compiles with the
following reason:
code=FFFFFFFFFFFFFFF8 compilationCodeReservationFailure
.
Stack Trace: N/A
.

Local fix

  • Increasing the size of the code cache may reduce the likelihood
of the problem occurring. Setting a single code cache and only
one compilation thread should avoid the problem, but may
negatively impact application performance.

Problem summary

  • The problem is caused by code paths that don't reset the
reserved flag on the code cache.

Problem conclusion

  • This defect will be fixed in:
6.0.1 SR8
7.0.0 SR7
.
The JIT has been modified so that a code cache is not left in
the reserved state.

Temporary fix

  • 



Comments


    

  • 



APAR Information




    

  • APAR number
    IV51764
    • 

  • Reported component name
    JIT
    • 

  • Reported component ID
    620700124
    • 

  • Reported release
    260
    • 

  • Status
    CLOSED  PER
    • 

  • PE
    NoPE
    • 

  • HIPER
    NoHIPER
    • 

  • Special Attention
    NoSpecatt
    • 

  • Submitted date
    2013-11-06
    • 

  • Closed date
    2013-11-18
    • 

  • Last modified date
    2014-01-03
    • 





    

  • 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
    JIT
    • 

  • Fixed component ID
    620700124
    • 



Applicable component levels


    

  • R260  PSY
       UP
    • 








      
              
                            

              

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Document Information


            

            


                        

            Modified date:
            

            03 January 2014
            

            
                      

        


        

        


      

    

  



    

  

  
    
            

          
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