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Re: Current FSFS performance [RAW]

From: Stefan Fuhrmann <stefan.fuhrmann_at_wandisco.com>
Date: Wed, 2 Jul 2014 16:13:31 +0200

Here the processed results. They show the expected
benefits of packing as well as f7 on HDD. Issues found
with faster storage (such as hot disks) have been
addressed and the results measured and compiled as a
second PDF. The PDFs contain test setup descriptions,
compiled results and explanations for those results.

Major findings for Linux:
* There was significant CPU overhead for f7 with small
  caches. That's fixed now and access costs are roughly
  the same as in f6.
* Non-packed repos perform roughly the same in f6 and f7.
* Packed repos are faster in general and f7 is even faster,
  progressively so with larger caches - if there is I/O at all.

* Differences between RA layers are not format-specific.
* ra_serf delivers the least consistent performance as it
  seems to decide dynamically how many connections to
  use. A fast server answer seems, therefore, to lead to
  slower throughput *per client* (but higher in total). This
  is format independent.

Test config rationales:
* "slow" config is our very conservative default.
* "medium" is for users that have heard about caching
  and sprinkle "-M 256" like pixie dust everywhere.
* "fast" is for users that actually read documentation.
  They use larger caches (1G here to make it suitable
  for 32 bit systems as well) and enable all advanced
  options. All tests used the same options (no specific tuning).

Next steps - in roughly that order:
* I'll write up a wiki page on what makes repo testing
  hard and what I learned about it, i.e. how to conduct
  future performance testing.
* Review & comment on Ivan's results.
* Test Windows VM + SAN setup at our data center to
  get more data points. This will easily take a week to do.

-- Stefan^2.

Received on 2014-07-02 16:14:02 CEST

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