paul@actrix.co.nz (Paul Gillingwater) (03/04/90)
Hi, could someone tell me please about MUMPS. I have been asked to do some system performance tweaking on a MUMPS-based medical records system (no names, no pack-drill), running under HP/UX on an HP9000/835. It runs very slow at times, with around 40 second response times for simple queries. I've tried increasing the number of semaphores and shared memory space, but it still runs slow. My problem is that I have absolutely NO documentation on MUMPS. I understand it runs as a hosted operating system under UNIX, and may be a hierarchial database structure, but I have no idea what sort of drain it places on system resources, buffers, etc. Does anyone have any experience in tuning the kernel to improve performance with MUMPS under HP/UX? Thanks. -- Paul Gillingwater, paul@actrix.co.nz
johnny@edvvie.at (Johann Schweigl/104857600) (03/10/90)
From article <1990Mar4.041009.27532@actrix.co.nz>, by paul@actrix.co.nz (Paul Gillingwater): > Hi, > could someone tell me please about MUMPS. I have been asked to do some > system performance tweaking on a MUMPS-based medical records system (no I've done some MUMPS-Tuning on HP-UX last year. Unfortunately, I can't find the docs now. We've done some relatively simple things and achieved satisfying performance. 1) watch your memory usage (sar or system monitor). If you get sometimes *VERY* bad performance and sometimes not, you probably have a paging problem. 2) try to put your MUMPS database files on a fresh, clean filesystem. dd your files to tape, clean file system, copy files back. This avoids file fragmentation. 3) if you have more than one or two database files, try to distribute them over different disks. This allows outstanding I/O's to be performed synchronously where possible. Avoid large disks, take more small drives. 4) we tried raw devices, did not change much, but saves UNIX buffer pool space. May help if you have only few RAM. 5) Up to now, nothing was MUMPS specific. Now I would need the manuals. There was a MUMPS utility, that lets you reconfigure your system. One of the menu choices deals with MUMPS buffers. Two parameters, called 'buffer treshold low' and 'buffer treshold high', along with a total buffer size, control MUMPS' own caching behaviour. Setting the treshold high-parameter to a large value (at least larger than the default) reduces buffer flushing and saves I/O. The treshold low-parameter had something to do with buffer reuse (or something like this) and I believe I reduced it significantly, compared to the default value. Can't remember exactly. Last, look how much RAM you have left over when the system runs under typical load condition, and configure as much buffers for MUMPS as you can get. You MUST not run into heavy virtual memory usage (see 1). Also, you may cross a breakeven point, after which adding more buffers does not increase performance. Just try a little, configure, run some benchmarks, reconfigure, and so on. Let me know if something helped. Regards, Johnny -- This does not reflect the | Johann Schweigl | DOS? opinions of my employer. | johnny@edvvie.at | Kind of complicated I am busy enough by talking | | bootstrap loader ... about my own ... | EDVG Vienna |