Re: KAIO vps, and bufwaits

Doug Hayes wrote: > > Neil, > > The number of kio vps is determined by the number of cpu vps > configured on your instance. I also think that you get a max queue of > 16 pretty quickly. I have seen my queue lengths on a heavily loaded > system reach 32. Correct. > Does anyone know what a high queue length is? Does a highr queue > length indicate a disk bottleneck or can adding physical cpu's (and > cpu vps) to the box help? For AIO queues, a long maximum length >25 or a consistent queue length >10 for the gfd queues indicates IO requests are not being serviced fast enough. But for KAIO queues, a length of 32 is not as meaningful because IDS often places big buffer (32 pages) requests on the queue. So I guess for KAIO, a length consistently >32 would indicate a need for more CPU VPs. Not that I've seen that, or had the chance to play on a box with spare CPU power. :-) Hope that helps, -- Mark. +----------------------------------------------------------+-----------+ |Mark D. Stock - Informix SA http://www.informix.com |//////// /| |mailto:mdstock@informix.com FAQ http://www.iiug.org |///// / //| | +-----------------------------------+//// / ///| | Tel: +27 11 807 0313 |If it's slow, the users complain. |/// / ////| | Fax: +27 11 807 2594 |If it's fast, the users keep quiet.|// / /////| |Cell: +27 83 250 2325 |Therefore, "No news: travels fast"!|/ ////////| +----------------------+-----------------------------------+-----------+