Re: What is bufwaits (onstat -p)

"Art S. Kagel" wrote: > > The bufwaits indicates when a thread has to wait to read a page into a > buffer from disk usually this is caused by the LRU Queue to which the thread > has hashed to acquire a buffer being locked by another thread trying to do > the same thing or needing to move a buffer from the 'clean' part of the > queue to the 'dirty' part so it can modify the page it contains. Sometimes > the condition is caused by buffer flushing activities for the same reason. > Another cause is the need to latch a buffer that already contains data to > move it to the MRU end of the queue. > > Increasing BUFFERS CAN help somewhat but the most effect is obtained by > increasing LRUS which reduces the probability that there will be contention > for the LRU that the thread hashes to (or the ones that it rehashes to > after spinning for too long). If there is still LRU contention even after > maxing LRUS out (128 in 7.[123]x) I thought the max LRUS was 256 for 32 bit? The max LRUS is certainly 512 for 64 bit. :-) The maximum number of page cleaners is 128. Perhaps this is were you got 128? Cheers, -- Mark. +----------------------------------------------------------+-----------+ | Mark D. Stock mailto:mdstock@mydas.freeserve.co.uk |//////// /| | http://www.informix.com http://www.informixhandbook.com |///// / //| | http://www.iiug.org +-----------------------------------+//// / ///| | |This email will self-destruct in |/// / ////| | |10 sec. If you received this email |// / /////| | |in error, sorry about the mess. |/ ////////| +----------------------+-----------------------------------+-----------+