On Nov 28, 2007 6:02 AM, Alan Ackerman <[EMAIL PROTECTED]> wrote: > interval. There may be a paging cost if you make the EVENT area too big, > since CP keeps adding event data to the end until it is full before wrapping.
That penalty is not real because CP will release the frames once all who eat from *MONITOR have consumed the data. A large event area does prevent events getting lost when the performance monitor is held back for some reason. Only on a very constrained system you may find CP page out portions of the DCSS before the performance monitor could process the data and release the page. That blocks the performance monitor on paging, and makes CP grow more data into the DCSS to cause more paging (re: death spiral). We believe this is a bug in z/VM, and it is not really a fix to make the DCSS small so that you lose performance data (that you may need to analyze the cause of the storage constraint). Rob -- Rob van der Heij Velocity Software, Inc http://velocitysoftware.com/
