One page must be the minimum. The memory fairies recently visited here so we have 6 systems that are undercommitted for memory at the moment. Each of them has exactly 1 page in use.
Marcy -----Original Message----- From: Linux on 390 Port [mailto:LINUX-390@vm.marist.edu] On Behalf Of Bill Holder Sent: Friday, June 17, 2011 11:20 AM To: LINUX-390@vm.marist.edu Subject: Re: [LINUX-390] z/VM page space > I'm curious about why CP would write pages immediately after IPL? At that > point, there is likely sufficient memory and paging isn't needed.. so why > not wait until it is? I'm sure there's a good explanation - just > wondering... > > Scott Rohling I can't really speak for how good the explanation really is, but I know of several cases where we're basically saving "for later" some data that will only needed in unexpected / exceptional circumstances and that needn't be kept resident. If we were writing such code anew these days, we might instead choose to put such data in a pageable virtual CP utility space, and leave it sitting there, to be paged out only if/when there is actual need (that's exactly how the Virtual Free Storage space I mentioned works) - but there is plenty of code which long predates such pageable CP utility spaces, that page things out explicitly rather than waiting for demand. And as always, if there's old code that isn't broken or getting in the way of new design changes, we're unlikely to change it, even if newer and better methods now exist - the usual cost / benefit / risk trade offs. - Bill Bill Holder, Senior Software Engineer IBM z/VM Development, Memory Management, Endicott, NY Phone: 607-429-3640 IBM TieLine: 620-3640 ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/ ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/
