WSS not adjusted for #polyclts

From: Alex Rousskov (rousskov@ircache.net)
Date: Thu Jul 13 2000 - 10:41:10 MDT


Hi there,

        While teaching Polygraph to compute the number of client-server
pairs in a bench, we have found a bug. Polygraph 2.5.2 does not adjust
working set size for the number of client-server pairs in the setup,
resulting in larger than needed WSS for request rates exceeding 400/sec.

We have a patch that attempts to fix the problem while making overall
PolyMix-3 configuration easier:
  http://polygraph.ircache.net/sources/patches/add_host_count.patch

The patch does three things:

    - adds the "client_host_count" field to the Bench object (PGL)

    - adds the clientHostCount() function to compute the number of
      client hosts based on the PolyMix-3 rules (PGL)

    - sets TheBench.client_host_count to clientHostCount(TheBench)
      and uses TheBench.client_host_count to adjust WSS and
      other parameters that depend on the number of client-server
      pairs (polymix-3.pg and polymix-3-guts.pg)

The patch modifies polymix-3*pg files. Please read the comments in
updated polymix-3.pg carefully before setting workload parameters: The
proxy cache size should now be specified *without* adjusting for the
number of client hosts; Polygraph will do all the adjustments for you!

To apply the patch, you will need to do something along these lines:

> cd polygraph-2.5.2
> fetch http://polygraph.ircache.net/sources/patches/add_host_count.patch
> patch < add_host_count.patch
> make clean all

Please apply the patch before starting the next test with 2.5.2.

Thanks,

Alex.



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