lucene-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Paul Smith <psm...@aconex.com>
Subject Re: Float.floatToRawIntBits
Date Wed, 16 Nov 2005 21:21:33 GMT
I can confirm this takes ~ 20% of an overall Indexing operation (see  
attached link from YourKit).

http://people.apache.org/~psmith/luceneYourkit.jpg

Mind you, the whole "signalling via IOException" in the  
FastCharStream is a way bigger overhead, although I agree much harder  
to fix.

Paul Smith

On 17/11/2005, at 7:21 AM, Yonik Seeley wrote:

> Float.floatToRawIntBits (in Java1.4) gives the raw float bits without
> normalization (like *(int*)&floatvar would in C).  Since it doesn't do
> normalization of NaN values, it's faster (and hopefully optimized to a
> simple inline machine instruction by the JVM).
>
> On my Pentium4, using floatToRawIntBits is over 5 times as fast as
> floatToIntBits.
> That can really add up in something like Similarity.floatToByte() for
> encoding norms, especially if used as a way to compress an array of
> float during query time as suggested by Doug.
>
> -Yonik
> Now hiring -- http://forms.cnet.com/slink?231706
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: java-dev-unsubscribe@lucene.apache.org
> For additional commands, e-mail: java-dev-help@lucene.apache.org
>
>


Mime
View raw message