BIND 10 #1750: add "at origin" option in ZoneFinder::find() and support it in in-memory

[BIND 10 Development]

#1750: add "at origin" option in ZoneFinder::find() and support it in in-memory
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                   Reporter:         |                 Owner:  jinmei
  jinmei                             |                Status:  reviewing
                       Type:  task   |             Milestone:
                   Priority:  high   |  Sprint-20120320
                  Component:  data   |            Resolution:
  source                             |             Sensitive:  0
                   Keywords:         |           Sub-Project:  DNS
            Defect Severity:  N/A    |  Estimated Difficulty:  4
Feature Depending on Ticket:  auth   |           Total Hours:  0
  performance                        |
        Add Hours to Ticket:  0      |
                  Internal?:  0      |
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Comment (by jinmei):

 Replying to [comment:10 vorner]:

 > Ah, right, so I compared it with query_bench against the place I
 branched (so the difference is fair, not agains some other optimisation we
 included in the meantime). And the difference is rather small:
 >
 > With the change:
 > {{{
 > Benchmark with In Memory Data Source
 > Processed 4000000 queries in 52.754674s (75822.67qps)
 > }}}
 >
 > And without:
 > {{{
 > Benchmark with In Memory Data Source
 > Processed 4000000 queries in 53.023560s (75438.16qps)
 > }}}
 >
 > I think it is not worth it. Do you agree we should drop the branch,
 then?

 Okay, if that's really what it provides I agree it's worth adding.
 I'd hold off for a while, however, until we merge other major
 optimizations, then check the effect of this on top of them.  Maybe
 other overheads are too significant and hide the effectiveness of this
 one.  Until then we could either keep it in the review queue or
 temporarily pull it from there and make it in the "open" status.

 BTW, what kind of data did you use the above test?

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Ticket URL: <http://bind10.isc.org/ticket/1750#comment:11>
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