Re: chekcpoints, BUFFER settings, and optimization

"Art S. Kagel" <kagel@bloomberg.com> wrote: +Dave I have to disagree. I agree that additional cleaners are of +limited use during normal LRU writes but they are needed for fastest +checkpointing. Since at checkpoint time each chunk is assigned to +another cleaner thread until the threads are exhausted, and since that +one thread, as has already been pointed out, is only scheduling the +actual I/Os with either the AIO VPs or KAIO VPs, that thread will block +on each I/O that it schedules and single thread writes to your disks. +You must have multiple cleaners, even with a single CPU VP, since the +other cleaners can wake and schedule the I/Os that they are responsible +for while the first cleaner is blocked waiting for I/O service. The cleaner threads do not block on the i/o calls. There are NO blocking calls whatsoever in the CPU VPs. Besides, if a cleaner thread "blocked", it would not be yielding the cpu vp, in which case having more cleaner threads than cpu vps would still not make any sense. I'm with Dave Williams on this one. Dave "That's just my opinion - I could be wrong." - Dennis Miller