[NTLUG:Discuss] Disk I/O timings.

[David Neeley]

This suggestion may not be practical for all I know (as I'm not a 
programmer!). However, when I was with a design and manufacturing company 
years ago we did quite a bit of work with various kinds of hardware and 
software disk cache setups. At that time, there were some similar issues 
that Steve describes in trying to optimize performance on the systems.

At that time, the main designer told me one day that he had had to insert 
some special instructions in his code temporarily to flush the cache so he 
could begin to understand how everything was working.

The caching disk controllers had commands for such things. We used some DPT 
and some from other vendors back in "pre-history" (this was the first 486 
PC, built by a little company over in Longview called Cheetah International).

It could be that the disk vendors could fill you in on a similar technique 
so you could incorporate such instructions at varying places in the 
execution of the code and see what difference it makes when you are sure 
the data is not coming from the cache.

I hesitated to speak up, since it's been so many years and since as I said 
I'm not a programmer. However, it seemed to work for the Cheetah systems 
and it may work for you, too!

David