Jens Vagelpohl wrote at 2006-1-31 15:07 +0000: >On 31 Jan 2006, at 15:01, Jake wrote: > >> http://plone.org/documentation/how-to/threads-vs-cache-size > >That article contains little information to back up the conclusions, >and some of it is patently wrong. Another case of hearsay and half- >thruths being propagated by well-meaning but uninformed parties.
There is a convincing example (I think from Matt Kromer) what happens to "mean response time" when the number of threads is increased from 1 to 2: Assume you have 2 units of work. If you have a single thread, 1 unit is done, then the second. The mean response time is (1 + 2) / 2 = 1.5. Now assume you have two threads (but a single processor). Both threads work (quasi) parallel but have only half of the processor power. Both will take 2 time units to perform their unit of work. The mean response time is (2 + 2) / 2 = 2. You get the same ratios whenever you double the number of threads (but keep the number of processors and all your work is CPU bound). Things become more difficult when you have a mix of very small requests and very long requests. You then may want a higher level of concurrency to not let the small requests being blocked by the long ones. -- Dieter _______________________________________________ Zope maillist - Zope@zope.org http://mail.zope.org/mailman/listinfo/zope ** No cross posts or HTML encoding! ** (Related lists - http://mail.zope.org/mailman/listinfo/zope-announce http://mail.zope.org/mailman/listinfo/zope-dev )