Re: concurrency problem in 5.07

In article <u9yapkhvym.fsf@voss.bellcore.com>, robert schmidt <schmidt@voss.bellcore.com> writes > > >Hi, > >We have an old sun ss1000e with solaris 2.4 and informix 5.07 on it. >This system has a strange and unexplainable performance problem: >when more than two queries run concurrently, the response time is >highly degraded. All of the data that the queries are reading >is in informix buffer cache, so there is no i/o time. >The inquiries are read only (cursor stability), Cursor stability does take locks... >so not too much locking should be taking place.... >So, why can the system not take advantage of the 6 CPUs that it has. > >response time example: >one process 27 seconds >two processes 33 seconds (average) >three processes 66 seconds (average) >four processes 96 seconds (average) > >It seems that up to two processes can efficiently run concurrently. >Beyond that, the system degrades quite seriously. > >So far as I can tell, there is nothing interesting in 'sar' reports >when the system is showing this degraded performance. The overall >CPU utilization actually goes down as more processes are run >concurrently. > >Has anyone seen this before ? >Is there a know fix ? > >The only idea we have at this time is adjusting the 'SPINCNT' configuration >parameter... Perhaps double it to 600. Any thoughts on this idea? > > >thanks > >rob -- David Williams Maintainer of the Informix FAQ Primary site (Beta Version) http://www.smooth1.demon.co.uk Official site http://www.iiug.org/techinfo/faq/faq_top.html I see you standin', Standin' on your own, It's such a lonely place for you, For you to be If you need a shoulder, Or if you need a friend, I'll be here standing, Until the bitter end... So don't chastise me Or think I, I mean you harm... All I ever wanted Was for you To know that I care