IBM Support

During a period of high usage of our TPF system, what order should we shut down traces?

Question & Answer


Question

During a period of high usage of our system, what order should we shut down traces?

We are expecting a dramatic peak increase in usage soon. We understand that in our z/13 environment, C function trace has high overhead due to STCK/STCKE usage. We hope to understand the correct order for us to shut down traces if necessary due to high CPU usage. The ZSTRC DISPLAY for the system is as follows:

  STRC0013I 16.14.07 SYSTEM TRACE OPTIONS
  TYPE OF SYSTEM TRACE          KEYWORD  STATUS
   ECB TRACE                    TRACE      ON
   FUNCTION TRACE               FUNCTR     ON
   EXTENDED FUNCTION            FUNCEXT    ON
   TPF ENTER/BACK TRACE         ENTER      ON
   TPFDF ENTER/BACK TRACE       DFENTER    OFF
   IO TRACE                     IO         ON
   CCW TRACE                    CCW        OFF
   SYSTEM LOG                   SYSLOG     ON
   BRANCH TRACE                 BRANCH     OFF
   ECB HEAP TRACE               EHEAP      ON
   HEAP CHECK                   HEAPCHECK  OFF
   SOCKET TRACE                 SOCTRACE   OFF
   REGISTERS                    REGS       ON
   BLOCK CHECK                  BLKCHK     OFF
   IBM DEBUGC TEST              DEBUGIT    OFF
   IBM DEBUGC LOG               DEBUGIL    OFF
   USER DEBUGC TEST             DEBUGUT    OFF
   USER DEBUGC LOG              DEBUGUL    OFF
   BRANCH RELATIVE TARGET CHECK BRCHECK    ON
   IDLE TIMER                   IDLETMR    OFF
  END OF DISPLAY

Answer

The recommendation is to shut trace functions off according to what you expect  would give you the most payback in terms of additional MIPS, and still have certain function available to debug.
If you happen to know the percentage of gain for each function in your system when you turn it off, you can use that as a basis for what to turn off.

Otherwise, here is a suggested 3 step process based on the trace functions that are shown as ON in the display that you provided:

  1. Turn off the following traces first:
    BRANCH RELATIVE TARGET CHECK BRCHECK
    FUNCTION TRACE
    EXTENDED FUNCTION
    REGISTERS
  2. Turn off the following traces next:
    TPF ENTER/BACK TRACE
    IO TRACE
    ECB HEAP TRACE
    ECB TRACE
  3. Turn off the following traces last:
    SYSTEM LOG

[{"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSZL53","label":"TPF"},"Platform":[{"code":"PF036","label":"z\/TPF"}],"Component":"","Version":"","Line of Business":{"code":"LOB35","label":"Mainframe SW"}}]

Document Information

Modified date:
09 April 2020

UID

dwa1249301

Page Feedback