Lazy Page Cleaners; Was: tuning checkpoint duration

I guess nobody heard us ... In article <7gm2v8$g1r$1@nnrp1.dejanews.com>, ralph.halter@pac.panmail.com wrote: > In a performance tuning class working with IDS 7.30 we had the impression that > the LRU_MIN/MAX parameters were not adapted for use with the redesigned new > classes (priority levels) of dirty pages. Before 7.30 there was only one class > of dirty pages; now there are several priorities (onstat -R) and not all are > cleaned according to the same rules - or so I understood. If this is true then > all our common checkpoint tuning wisdom regarding low LRU_MIN/MAX is not valid > anymore ... > > Would one of the Internal Architecture Wizards like to comment or clarify? > > Cheers. > Ralph. > > In article <7gl52u$nfv$1@nnrp1.dejanews.com>, > Lyzander Marantal <zandy@my-dejanews.com> wrote: > > I have also observed this kind of behavior on IDS 7.24UC7 on Solaris. I've > > got 200,000 buffers, 5 CPU VPS, 20 LRUS, 20 Page Cleaners, LRU MAX 15, LRU > > MIN 10, lots of disks. I've seen my LRU queues reach as high as 100% with > > only a few cleaners doing their job. This resulted to foreground writes bec. > > the other page cleaners were lazy. > > > > This was on a particular load job. I know, I should have increased LRU MIN/MAX > > to maximize load performance. I just wanted to see what the engine would do. > > > > By the way, you could see it clearly using DB/Cockpit, Shared Memory section. > > Yup, the other page cleaners were definitely lazy. Bad page cleaners. :-) > > > > Lyzander > > > > In article <372DCFA8.73FA377C@computer.org>, > > Jay Walters <jwalters@computer.org> wrote: > > > I know this is a common question, but I've tried to implement the common > > > wisdom and I'm still having trouble. > > > > > > I'm running IDS 7.3TC7 on Windows NT 4.0 sp3. I've got 290K buffers, 15 > > > LRUs and 5 cleaners. LRU_MAX_DIRTY is 1, LRU_MIN_DIRTY is 0. > > > Checkpoints are every 15 minutes. I only have two disks, and I've tried > > > to split the I/O down the middle, 1/2 on each. > > > > > > My environment has a fair number of writers and queries which need to > > > complete quickly (< 10seconds). > > > > > > I often see the cleaners idle (onstat -F) even with 10K dirty pages > > > (>3%). Something causes them to wake up and clean, but they don't > > > really keep the LRUs clean enough to keep my checkpoints short. My > > > checkpoints are taking 30-60 seconds which is way too long. > > > > > > If all the LRUs are over LRU_MAX_DIRTY, why don't the cleaners wake up? > > > Or are they on some type of timer? > > > > > > I would appreciate any ideas or comments... > > > > > > Cheers > > > > > > > > > > -----------== Posted via Deja News, The Discussion Network ==---------- > > http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own > > > > -----------== Posted via Deja News, The Discussion Network ==---------- > http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own > -----------== Posted via Deja News, The Discussion Network ==---------- http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own