Martin, Except for when the compression assist instructions were in millicode on the G4 and G5, the hardware compression from Compression Services has always had am asymmetric cost for DFDMS compression. I remember some early documentation from IBM when it was first introduced in DFSMS that quoted 12 instructions per byte to compress, and two instructions per byte to decompress.
Ron > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of > Martin Packer > Sent: Thursday, December 02, 2010 3:36 AM > To: [email protected] > Subject: Re: [IBM-MAIN] Hardware-assisted compression: not CPU-efficient? > > Ron, is it generally the case that CPU is saved on read? I'm seeing QSAM > with HDC jobsteps showing very high CPU. But then they seem to both write > and read. Enough CPU to potentially suffer from queuing. > > (And, yes, I know you were talking about a different category of HDC > usage.) > > Martin Packer, > Mainframe Performance Consultant, zChampion > Worldwide Banking Center of Excellence, IBM > > +44-7802-245-584 > > email: [email protected] > > Twitter / Facebook IDs: MartinPacker > > > > > > Unless stated otherwise above: > IBM United Kingdom Limited - Registered in England and Wales with number > 741598. > Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU > > > > > > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: GET IBM-MAIN INFO > Search the archives at http://bama.ua.edu/archives/ibm-main.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
