Hello -
You might be seeing issues with physical dasd retrieval of the data. But that is just a guess. Have you looked at adding STRNO on the VSAM definition or using RLS to provide the records to be instorage? In your JCL for the job, have you coded BUFND, or BUFNI or BUFSP? Could you provide the LISTC ENT(vsam-name-here) ALL for us to review? What are your share options? When was the Cobol program last compiled and lked? What version of Cobol was being used when it was last compiled and lked? Has a review of the Cobol program logic been done to see if any performance can be gotten there? What version of z/OS are you running on? Are there any other processes using this VSAM dataset when it is being accessed by this program? DB2, CICS, etc.... Lizette > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] On > Behalf Of Arun Venkatratnam > Sent: Friday, January 05, 2018 5:20 PM > To: [email protected] > Subject: VSAM Performance - CPU reduction > > Hi All, > > We are looking to improve the performance of a COBOL program that processes 2 > VSAM files. The first file is the I/P file and every record read from the > input VSAM file is searched for a matching record in the other file and a > report is written. The program also applies some business rules while > comparing each matching record. > > The I/P file is read sequentially while the other file is read in a skip > sequential basis. The test files that were used had 32M records each while > production files have 110M records each. > > Attached is the strobe report from the execution of the test job. The test > job takes nearly 7 CPU minutes and was profiled to capture about 1 CPU minute > of execution time. > > We are attempting to optimize the VSAM access to these files as it is seen to > take more than 50% of the CPU consumed by this job. > > In the 'Attribution of CPU execution time' section, we see that the major > contributors are the components 'QSAM INIT I/O & EXITS' (Module IGZEQBL) and > PARTITION COMMUNICATION. > > Could you please help us understand: > > 1.What these components are > 2.Why is QSAM access used instead of VSAM I/O access. > 3.What needs to be done to reduce the CPU consumption by these components. > > Thank you > > Arun > > > ----------------------------------------------------------------------------- > ----------------------------------------------------------------------------- > -------- > > 1Strobe* PERFORMANCE PROFILE PROGRAMA > 01/02/2018 PAGE 42 > > - #ACE ** ATTRIBUTION OF CPU EXECUTION > TIME ** > -.COBLIB IGZCPCO IGZEVIO VSAM INPUT/OUTPUT > ---------------------------WAS INVOKED BY--------------------- ----------- > ------VIA----------------------- CPU TIME % > XACTION MODULE SECTION DESCRIPTION MODULE > SECTION DESCRIPTION SOLO TOTAL > > .LELIB CEEBINIT LE/370 BATCH INIT/TERM > .32 .32 > .LELIB CEEBINIT LE/370 BATCH INIT/TERM IGZEQBL > QSAM INIT I/O & EXITS 1.93 1.93 > > XACTION MODULE SECTION LOCATION LINE SOURCE TEXT MODULE > SECTION DESCRIPTION > > PROGRAMA PROGRAMA 003522 > 1.30 1.30 > > ----- ----- > > 3.55 3.55 > -.VSAM IDA019L1 VSAM RECORD MANAGEMENT > ---------------------------WAS INVOKED BY--------------------- ----------- > ------VIA----------------------- CPU TIME % > XACTION MODULE SECTION DESCRIPTION MODULE > SECTION DESCRIPTION SOLO TOTAL > > .LELIB CEEBINIT LE/370 BATCH INIT/TERM IGZEQBL > QSAM INIT I/O & EXITS 1.84 1.84 > .LELIB CEEBINIT LE/370 BATCH INIT/TERM IGZEQBL > CURRMEM QSAM INIT I/O & EXITS 4.34 4.38 > .LELIB CEEBINIT LE/370 BATCH INIT/TERM IGZEQBL > DVFILE QSAM INIT I/O & EXITS .03 .03 > .LELIB CEEBINIT LE/370 BATCH INIT/TERM IGZEQBL > PREVMEM QSAM INIT I/O & EXITS 22.48 22.51 > > XACTION MODULE SECTION LOCATION LINE SOURCE TEXT MODULE > SECTION DESCRIPTION > > PROGRAMA PROGRAMA 003522 IGZCPCO > CURRMEM PARTITION COMMUNICATION 4.15 4.19 > PROGRAMA PROGRAMA 003522 IGZCPCO > IGZEVIO VSAM INPUT/OUTPUT .57 .57 > PROGRAMA PROGRAMA 003522 IGZCPCO > PREVMEM PARTITION COMMUNICATION 16.80 16.80 > > ----- ----- > > 50.22 50.32 > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, send email to > [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
