Re: Page cleaners & LRU contention...

In article <362F4074.C8744205@aethos.co.uk>, Graham Mitchell <graham.mitchell@aethos.co.uk> writes >Hi guys and gals, > ( On HP-UX 10.20 K-Series 6 CPU ODS 7.24UD6) > > I recently upped the number of page cleaners on a > real time system with 16 chunks from 8 to 16. > > ( it seemed like a good idea ) > > It had 8 LRU queues LRUMAX/MIN at 8 and 4 > and 30,000 BUFERS . i.e a maximum of 2.3 Mb to write out ever > during a checkpoint. > > The checkpoints have gone up from 1 to 4 seconds > > The question is this : > Is this because the cleaners lock the LRU queue while they > write out the sorted pages that have been allocated to them ? Nope, you have one cleaner per queue > Or, is it more likely that there are groups of cleaners fighting > over a single disk.... Yep, chunks need to allocated round-robin across at least 16 disks for this to work.. > > This is a super fast auto RAID box, so disk I/O should be > dead quick . > > I have never got to the bottom of this question, even after > scouring the books so any light shed would be appreciated > > best Regards > Graham Mitchell > > >-- > /| /| > || ,,,// || > || ( O o ) || >+----------------))-----------------oOOo-(_)-oOOo----))---------------+ >| Graham Mitchell | >| Aethos Communications | >| graham.mitchell@aethos.co.uk | >| .oooO Phone: +44956324833 | >| ( ) Oooo. | >+----------------------------------\\ (----( )-----------------------+ > \\_) ) / > (_/ > > -- 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