IBM Mainframe Discussion List <[email protected]> wrote on 10/31/2011 03:25:05 PM:
> On 10/31/11 13:59, Edward Jaffe wrote: > > On 10/31/2011 10:10 AM, Mark Jacobs wrote: > >> We just started using the zOS Runtime Diagnostics under zOS 1.12 and > >> while I understand most of what it's telling us, I don't fully > >> understand what it's trying to tell me, or what I can do about it > >> when it reports on a HIGH LOCAL LOCK SUSPENSION RATE. > > > > Local lock suspension occurs when some executing code attempts to get > > the local lock (which is required for many services e.g., STORAGE) and > > another unit of work already has it. The requester is suspended until > > the lock is released by the other unit of work. > > > > If the rate is high (above average), it usually means some code is > > doing significant processing with the local lock held. It's not > > necessarily 'wrong'. Such statistics are a 'heads up' for the > > programmer(s). Is it your code that's executing? Or someone elses? > > > > Do you have 'Vsm UseZosV1R9Rules' coded in DIAGxx? Using the new rules > > can make STORAGE run faster, thus reducing local lock contention. YMMV. > > > > We're seeing it often for the HSM address space. We have UseZosV1R9Rules > set to No in Diagxx. > > -- > Mark Jacobs > Time Customer Service > Tampa, FL RTD analyzes a System Trace snapshot to determine that there is a HIGH LOCAL LOCK SUSPENSION RATE. I have observed in the system trace of various dumps that although HSM uses cell pools for automatic storage in some of its modules, there are several other HSM modules which are invoked for every write to a tape which do Getmain/Freemain for automatic storage. So when HSM has multiple TCBs doing this concurrently, that could lead to local lock contention. I mentioned that to HSM development a couple of years ago. I don't know if it has been changed in newer releases. Jim Mulder z/OS System Test IBM Corp. Poughkeepsie, NY ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
