But I do not think that "memory-bound" is right for most of our processes.

Well, I was only talking about the one process I thought you were describing (extracting a very large volume of data) and I did indicate it was a guess based upon your description, by using the word "probably"; so no biggy.

The thing I was getting at is that XXX-bound: means that performance (measured in wall-time not cpu time) is constrained by XXX. That is:

  1. CPU-bound: If you could insert a faster processor -- with nothing else changed -- the process would complete sooner.
  2. IO-bound: If you could speed up IO -- with nothing else changed -- the process would complete sooner.
  3. Memory-bound: If you added more memory -- with nothing else changed -- the process would complete sooner.

With DB apps (often; not always), things get muddy because: a) they often have bursts of both cpu-intensive & IO-intensive processing; b) often a lot of the cpu-intensive work (searching/selecting/sorting/grouping) is done by a completely different process (the DB engine); often-as-not on a completely different box or even cluster of boxes.

So when trying to categorise the overall processing (rather than the individual process) for a given task; you have to access the complete end-to-end processing requirements of that task.

Often, the client application itself would be considered IO-bound because it spends the greatest proportion of its time waiting for IO from the DB.

But if you consider the overall processing, it might be considered cpu-bound because the IO-rate from the DB is limited by cpu-bound calculations within the DB.

But finally, the overall thing might be memory-bound because the DB engines processing requires it break its cpu-intensive calculation into chunks, because the overall dataset it is processing is greater than can be loaded into its memory.

Bottom line is that the essentially throw-away comment in that other thread, that started this one, are very generic: all else being equal, running M processes, N-at-a-time on an N-core system will be faster than running those same M processes all concurrently; but as I showed above, all-else is very rarely equal.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority". I'm with torvalds on this
In the absence of evidence, opinion is indistinguishable from prejudice. Agile (and TDD) debunked

In reply to Re^4: Useful number of childs revisited [SOLVED] by BrowserUk
in thread Useful number of childs revisited [SOLVED] by karlgoethebier

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