Re: More CPUVPs than processors

Mark said: > Has anyone found a benefit to running more CPUVPs than processors with > 9.4? > > I have been running some load tests on a dual CPU Itanium/HPUX machine > with 8gb ram connected to an EMC disk array. The instance is configured > with 2 million buffers, 127 cleaners and LRUs. Rather than configure the > instance specifically for bulk loading I have left the instance > configured for OLTP activity - in real life many of the jobs that run > during normal hours are similar in nature. Instance has 4 dbspaces, 4 > spaces used for indexes, 3 temp spaces and a rootdbs. KIO is enabled. > All spaces are on the same set of disks [no control over that]. Indexes > are created after the data has been loaded. > > During the load I am finding that the cleaners do not manage to keep up. > The LRU min/max are 0.5 and 0.7 respectively. The modified queues will > reach as high as 15% dirty. If I have the system configured with 2 > CPUVPS there will be idle cleaners. CPU usage rarely exceeds 25-30%. > Checkpoints will take many 100s of seconds. > > I have found that adding CPUVPS results in all the cleaners being active > all the time. The queues are much shorter, rarely exceeding 4% and > checkpoints generally last no more than a minute. The extra kio threads > use about 20-30% of the total CPU time used by all the KIO threads. > > The results are very repeatable. I have dynamically added/removed CPU > VPS during large table loads and seen the effect on the queues and > checkpoints. It might be an Itanium-specific thing. It's certainly not generally applicable to 9.40. -- Bye now, Obnoxio "C'est pas parce qu'on n'a rien ' dire qu'il faut fermer sa gueule" - Coluche "I'm trying to see things your way, but I can't get my head up my ass" - JCH "Ogni uomo mi guarda come se fossi una testa di cazzo" - Marco You are better at sex than anyone. Now all you need is a partner. I went to the airport to check in and they asked what I did because I looked like a terrorist. I said I was a comedian. They said, "Say something funny then." I told them I had just graduated from flying school. -- Ahmed Ahmed http://members.rogers.com/2remedy/images/smilies/banners/RTFM.gif sending to informix-list