Re: Keeping clean pages in shared memory

We had a similar discussion on our project not only about read pages (which as Malcolm points out is moved to the beginning of the queue when read) but what happens when the page cleaner flushes a dirty buffer? Does the buffer end up in the free list or can it still be used to do a cached read? We carried out some tests which reveal that a flushed page remains in the LRU queue. This means that it is still available for cached reads. We wanted to know this because we didn't know if page cleaning and checkpoints had a detrimental effect on write caching. It appears that it doesn't so we felt we could change the LRU min and max dirty to a low value and not affect performance. David W Chan Objective Research Ltd dwc@cix.compulink.co.uk