Re: vmstat -s
>What does "revolutions of the clock hand" mean in a vmstat -s? > >I read somewhere that if "revolutions of the clock hand" > "uptime" then you >have major problems. We have a system that just recently had "revolutions of >the clock hand" = 10 and uptime was 2 days.... needless to say the shortly >there after the system panicked. > >I can't find any documentation on the vmstat -s information. > >Thanks in advance.. >Val It refers to the NRU paging algorithm. Clock [not system clock() ] refers to the clearing of the referenced bits on the memory pages. Each and everytime pageout runs x pages are examined by the front and back hands of the clock. The front hand clears the referenced bits. Otherwise pages that already have their reference bit set are stolen from the current process and put on the freelist. Modified stolen anon pages are written to swap space and freed. When free memory fails below lotsfree, pageout is run 4 times a second, if you hit desfree then pageout is run every clock() (the system clock() function). Where cachefree comes in to the equation I don't know. Assuming we are still on Solaris, AIX has a goodish explaination of vmstat but it uses a different paging algorithm ie pseudo lru, then there is very little documentation. You can check out http://www.sunworld.com/swol-09-1996/swol-09-perf.html but it lacks depth. Getting the se toolkit would be a good move. [cutting] Paul Watson WF Software Ltd Tel: +44 1436 674729 Fax: +44 1436 678729 www.wfsoftware.com/informix # If you broke it, hide the evidence ********************************************************************** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by MIMEsweeper for the presence of computer viruses. www.mimesweeper.com **********************************************************************