As others have pointed out, accessing an active SFS directory can be a big contributor. I confirmed this by letting a machine sit idle for 2 hours while it had such a directory accessed. After 2 hours, I released the directory and it was disconnected 15 minutes later. In this case, I would expect to see VTIME incrementing because CMS is accepting the interrupts. If they are IUCV interrupts, that measure is blown out the door, too. Is there no such thing as an idle user anymore?
Regards, Richard Schuh -----Original Message----- From: VM/ESA and z/VM Discussions [mailto:[EMAIL PROTECTED] On Behalf Of Eginhard Jaeger Sent: Friday, January 27, 2006 12:03 AM To: [email protected] Subject: Re: Charging Time Well, I agree that knowing about everything that goes on behind the covers would be nice. While I cannot give you the explanation of CP's behaviour for this specific case, I can confirm from long experience what others have already written: TTIME **can** (and usually will) get incremented even for completely idle machines. As you apparantly already know the processing of messages from other virtual machines is one of the things that will increment TTIME. But do the exact causes matter for you? The fact is that it works this way, and any logic you implement to FORCE DISCONNECT virtual machines must obviously take this behaviour into account. So, instead of looking too hard at the TTIME value which you know to be unreliable as an 'idle' state indicator, better look for and test things that are more reliable, such as - VTIME - non-spooled I/Os - IUCV counts - ... If any of these are incremented there must have been some activity in the virtual machine. While that activity is still not guaranteed to have been initiated by the machine's owner (I assume that your intention is really to reduce the security exposure caused by unattended consoles), it's the best advice I can give. Unless you find an easy way to detect attention interrupts on user consoles .. It's along these lines that I implemented the idle user detection code for IBM's Performance Toolkit many years ago. Not perfect, maybe, but has been working well in practice. Eginhard Jaeger ----- Original Message ----- From: "Schuh, Richard" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Thursday, January 26, 2006 5:59 PM Subject: Re: Charging Time > We do have a performance monitor, but that was not the question. Rather, > the question was, "What can be happening that would cause an increase in > VMDTTIME for this machine?" > > In the case cited below, I had complete control of the CMS machine in > question and it was outwardly idle. Nothing was running under the covers > except CMS. No reader files were arriving, no messages, etc. I will try it > again after insuring that there is no SFS directory that is accessed. > > Regards, > Richard Schuh > > -----Original Message----- > From: VM/ESA and z/VM Discussions [mailto:[EMAIL PROTECTED] On > Behalf Of Brian Nielsen > Sent: Thursday, January 26, 2006 7:25 AM > To: [email protected] > Subject: Re: Charging Time > > Tracking how many pages are resident for the userid over time would help > answer your question. If you don't have a performance monitor to give you > that info, another userid issue periodic IND USER commands. > > Putting the userid in question into a disabled wait and/or CP READ would > eliminate code executing inside the virtual machine as a possible source. > If you wanted a different way to get a warm-fuzzy that it wasn't CMS > related processing, you could IPL a non-CMS system, like the standalone > loader. > > Brian Nielsen > > On Wed, 25 Jan 2006 13:08:21 -0800, Schuh, Richard <[EMAIL PROTECTED]> > wrote: > >>Is the time spent stealing pages charged to the user whose pages are > being stolen? If not, what else can add to the TTIME of an otherwise idle > user? >> >>Let me set the stage. We are being required to FORCE DISCONNECT any user > who has been idle more than x minutes (x still being debated). Trying to > test the routine that does this, I logged on a general user and let it sit > idle after falling through its PROFILE. It remained connected, so I could > see that there were no messages being received that might be counted as > TTIME. This user stayed connected for nearly an hour longer than the > specified limit. In reviewing statistics gathered using ESAMON, there were > several times during the period when the reported VMDTTIME was > incremented, which in turn, caused the idle clock to be restarted. After > several resets of the idle value, the user finally timed out and was > disconnected. When ESAMON reports TTIME to the macro being used, it > converts VMDTTIME to a decimal number rounded to 10000ths of a second, so > these periodic increments were stepping in 10ths of milliseconds, not > insignificant values for a z990. >> >>This happened fairly early in the morning. We do not observe anything > like it when we reach our normal daytime load. That is what made me think > that it may be page steals. The rationale is that the pages are stolen > more quickly when the machine is loaded, so they are all stolen very early > in the idle period, not causing a noticeable lengthening of it. With a > light load, there is much less a reason to steal pages; therefore it takes > a much longer period to steal all of the idle user's pages and they are > stolen in small clumps at random times, accounting for the unevenness of > the incrementing of TTIME. >> >> >>Regards, >>Richard Schuh >>======================================================================== >
