Re: very high "mt yield 0" on IDS 9.40

After thinking about this a little longer I changed my mind. Your thread spends a lot of time in the yield 0 state. This can be caused by the following: A thread running a query entirely on the buffer pool (or something similar) has to yield(0) occasionally to give other threads a chance to run. The high time spent in yield 0 state means that there are other competing threads which run after the yield(0). I assume your data is from a busy system? Only if the number of yield 0 events becomes excessively high, you have to worry about busy waits. But your data does not show this number. Michael Michael Mueller wrote: > rvb wrote: > >> looking at the wait statistics of my IDS 9.40 I find an ever >> increasing value for the "MT yield 0" condition. >> >> Up to my knowledge this means that threads are doing busy waits for >> other event's > > > Looks like it. > > (snip) > >> How can I try to track down the reason for this behaviour ? > > > That's difficult. Can you give us some more information? > > - scheduler statistics, number of vps from onstat -g glo > > - Do the threads hit use shm connections (notorious for yield 0)? > > - Any clues about what these threads are doing special? > > - What OS and what exact online version? Would it be possible to attach > a debugger to oninit (which is a risk in a productive environment)? > > Michael