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Re: [xml-dev] XML parsing @ 100MB-1000MB/sec/GHz with Parallel BitStreams

Hi Rob,

Those are very impressive figures! I downloaded your parser and did a 
quick test to compare it to Expat parsing a 1.1Gb XML file:

Expat: 21.0s (wallclock), 18.2s (user time)
Parabix: 21.7s (wallclock), 4.0s (user time)

I used the "markup_stats" program that came with Parabix. Clearly 
Parabix is spending less time with heavy CPU load (user time), but it 
still takes longer to parse when disk IO is included (wallclock time). 
Parabix also seems to take far more memory than Expat - proportional to 
the size of the document?

Can the IO and memory usage in "markup_stats" be improved, or is this an 
intrinsic problem with your approach to XML parsing?


Rob Cameron wrote:
> I am pleased to announce the availability of parabix-0.40, a high-performance
> XML parsing engine prototype that can parse text-oriented XML document
> on commodity processors at over 200MB/sec per processor GHz and 
> data-oriented XML documents at speeds approaching that.    At this point, 
> this includes correct parsing of correct documents and dispatch to markup 
> action routines using an in-line API for XML (ilax).    As the parabix stack 
> is built out to incorporate validation and object creation, I am expecting
> overall performance above 100MB/sec/GHz.  With linear speed-up on
> multicore processors and other improvements, 1000MB/sec/GHz is 
> forseeable.
> By way of comparison, XML Screamer (Koustalas et al, WWW 2006) performs
> parsing, validation and business object creation on commodity processors at
> the rate of 23-46 MB/sec per processor GHz (MB/sec/GHz), a substantial
> increase over the cited rate of 2.5-6 MB/sec/GHz for traditional validating
> parsers.
> This is very good performance for traditional character-at-a-time parsing,
> taking advantage of a collection of techniques such as optimization
> across layers and schema-based customization.  As a benchmark, 
> 100 MB/sec/GHz is cited as the limit on throughput achievable for a
> simple character-at-a-time scanning loop.
> My research is investigating the development of very high-speed text
> processing based on a fundamentally new approach:  using parallel bit
> streams to represent character data and the SIMD processor capabilities
> of commodity CPUs to process these bit streams.
> I have first applied these techniques to the problem of UTF-8 to
> UTF-16 transcoding, to achieve end-to-end speed-up of 3X to 25X
> compared with standard iconv and similar implementations.   The 
> open source implementation of u8u16 is available at
> http://u8u16.costar.sfu.ca/ and the results have just been
> presented to ACM PPoPP 2008 in Salt Lake City.
> Parabix (parallel bit streams for XML) is a research prototype that is
> nevertheless being designed to become the basis for a full XML
> processing stack.  The working code repository is now available
> as an open source code base under OSL 3.0.   
> http://parabix.costar.sfu.ca/
> I am hoping to accelerate development of parabix technology through the
> open source model as well as continuing the academic research project
> with a team of graduate students who are coming up to speed.    I have
> also created a spin-off company to oversee commercial development
> of the technology.
> However, in the context of discussion of XML performance issues and
> the next ten years of development of XML technology, I think that
> the work is sufficiently well advanced to support the following advice:
> Do not assume that XML processing performance is inherently limited
> by the nature of present-day character-at-a-time parsing technology.
> Intraregister and intrachip parallelism hold out a realistic promise of
> dramatic performance improvement on commodity processors.

John Snelson, Oracle Corporation            http://snelson.org.uk/john
Berkeley DB XML:        http://www.oracle.com/database/berkeley-db/xml
XQilla:                                  http://xqilla.sourceforge.net

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