In general I would not take this sort of profiler output too literally.
If floatToRawIntBits is 5x faster, then you'd expect a 16% improvement
from using it, but my guess is you'll see far less. Still, it's
probably worth switching & measuring as it might be significant.
Doug
Paul Smith wrote:
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
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