> -----Original Message----- > From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On > Behalf Of Tom Marchant > Sent: 12 April, 2017 15:03 > To: IBM-MAIN@LISTSERV.UA.EDU > Subject: Re: Paging subsystems in the era of bigass memory > > On Wed, 12 Apr 2017 06:28:05 +0000, Vernooij, Kees wrote: > > >From here, there the story still goes on IIRC: if DB2 again needs > >the data, it would be paged in in any normal task. However, DB2 > >is more intelligent: it keeps track of how long it takes to page-in > >the page or read it again from disk, in a I/O that is already running. > >If the latter is faster this is used and the aux slot is really > useless. > > Are you suggesting that before DB2 references a page containing a > buffer, it checks to see if it is paged out?
Yes. > And that if it is paged > out, > it doesn't use the record in the buffer, but instead reads it into a > different page? No, it checks its(?) statistics about page-in time and reading it directly from dasd and then decides which will be faster. I heard this years ago, when heavy paging systems might produce slow page-ins and adding a page to an in-progress pre-fetch could be faster. > That makes no sense to me. This does? Kees. > > -- > Tom Marchant ******************************************************** For information, services and offers, please visit our web site: http://www.klm.com. This e-mail and any attachment may contain confidential and privileged material intended for the addressee only. If you are not the addressee, you are notified that no part of the e-mail or any attachment may be disclosed, copied or distributed, and that any other action related to this e-mail or attachment is strictly prohibited, and may be unlawful. If you have received this e-mail by error, please notify the sender immediately by return e-mail, and delete this message. Koninklijke Luchtvaart Maatschappij NV (KLM), its subsidiaries and/or its employees shall not be liable for the incorrect or incomplete transmission of this e-mail or any attachments, nor responsible for any delay in receipt. Koninklijke Luchtvaart Maatschappij N.V. (also known as KLM Royal Dutch Airlines) is registered in Amstelveen, The Netherlands, with registered number 33014286 ******************************************************** ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
