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Re: NSE Nsock Binding Performance Results and Improvements
From: Patrick Donnelly <batrick () batbytes com>
Date: Wed, 15 Jul 2009 09:42:29 -0600

On Wed, Jul 15, 2009 at 9:39 AM, Patrick Donnelly<batrick () batbytes com> wrote:
On Mon, Jul 13, 2009 at 11:58 PM, Patrick Donnelly<batrick () batbytes com> wrote:
Attached is a PDF of the report.

Here is a summary of the report:

We conducted tests for three different script sets across two machines
with manually set parallelism values ranging from 10 to 100 (the
current default parallelism being 10). Graphs of numerous concurrently
running script threads (up to 900) consistently formed an exponential
decay regression for script scan time. One running script
(html-title.nse) would usually see a constant flat improvement across
the range of parallelisms (that is, no change in total scan time). The
timings for the scans showed that a parallelism of 40 got the most
benefit for each increase in parallelism.

Due to our results, we changed the parallelism value to 40 to get
increased performance by default out of NSE (revision 14264).

After recent discussion we have again changed the parallelism to a
lower value of 20 (revision 14303). The reasoning for only doubling
the previous parallelism of 10 is concerns about a significant niche
of NSE users that will be running on poor connections incapable of the
load demand a parallelism of 40 may introduce (especially at the
start). It should be noted that a parallelism of 20 is still a huge
improvement over 10 and in some scans caused a scan to take less than
half the time to run.

The current plan is to investigate a more dynamic solution that will
allocate the optimal amount of open sockets for the scan based on real
time network conditions.

-Patrick Donnelly

"Let all men know thee, but no man know thee thoroughly: Men freely
ford that see the shallows."

- Benjamin Franklin

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