Magma read performance

[Facundo Vozzi]

Hi Chris,
what kind of application is that? At work I'm working on a ten years old
production system with Oracle DBMS and it's 1 GB of size.

Thanks for share your analysis again,
Facu

On Wed, Nov 24, 2010 at 2:38 PM, Chris Muller <ma.chris.m at gmail.com> wrote:

> There has been interest in Magma's read and query performance lately,
> so I thought I would share results of a recent benchmark test.
>
> It's an actual application which does very heavy reading and writing
> to a Magma repository.  This test was 24GB of repository work, over
> two days.  My goal was to determine, once the persistent model becomes
> many times the size of RAM and HD access appeared to become the
> limiting factor:
>
>  - how fast is Magma, in terms of "objects per second" and in
> "kilobytes per second"?
>  - how fast is this relative to the speed when the repository was empty?
>
> Conclusion:
>
>  - Magma started at 4K objects per second (empty repository), 282K per
> second.
>  - Finished with 2.3K objects per second (6GB repository), 750K per second.
>  - Memory consumption by the image never exceeded 300MB.
>
> It is important to note, these times are from the client MagmaSession
> point-of-view, including the full server roundtrip plus
> materialization.  Also, as can be seen from the attached data, there
> were many requests which only brought back one or two objects which,
> while dramatically lowering the overall reported throughput, is
> actually a real-world scenario for applications.
>
> Verbose description:
>
> When the test first started the repository was tiny, and there were
> only ~4K server requests during a 5-minute monitored period.  The
> total number of objects read across all ~4K requests was ~17M for an
> average throughput of 4K objects per second (ops).  As the model grew
> in size and complexity, more and more objects during the 5-minute
> monitored intervals were required to perform application-posting of
> the same number of input records; doubling to ~8K server requests
> during a 5-minute period, however only a few more objects brought back
> (total 21M), for an average of 2500 ops.  32 hours after that, the
> rate of reads dropped to about 2300 ops.  This is due to two factors:
>
>  - the objects were larger (e.g., more pointers to other objects)
>  - they were less clustered (having been replaced with objects which
> could not be co-located with the original object)
>
>
>
> The fact that objects got bigger (e.g., more pointers to other
> objects) is corroborated by another stat, "the number of *bytes* per
> second" read off the HD in order to access those objects.  Initially,
> when the test first started, there were about 4K *requests* for
> objects in one of the first five-minute periods, which were read at a
> rate of 282K per second.  24 hours later, there were only 2 times as
> many requests for objects, but were read-and-materialized at a rate of
> 750K bytes / second.
>
>
>  - Chris
>
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