But to use it, we should change MMapDirectory to also use the mapping when writing to files. I thought about it, it is very simple to implement (just copy the IndexInput and change all gets() to sets())
----- Uwe Schindler H.-H.-Meier-Allee 63, D-28213 Bremen http://www.thetaphi.de eMail: u...@thetaphi.de > -----Original Message----- > From: Michael McCandless [mailto:luc...@mikemccandless.com] > Sent: Tuesday, June 16, 2009 4:22 PM > To: java-dev@lucene.apache.org > Cc: Alan Bateman; nio-disc...@openjdk.java.net > Subject: Re: madvise(ptr, len, MADV_SEQUENTIAL) > > Lucene could really make use of this method. When a segment merge > takes place, we can read & write many GB of data, which without > madvise on many OSs would effectively flush the IO cache (thus hurting > our search performance). > > Mike > > On Mon, Jun 15, 2009 at 6:01 PM, Jason > Rutherglen<jason.rutherg...@gmail.com> wrote: > > Thanks Alan. > > > > I cross posted this to the Lucene dev list where we are discussing using > > madvise for minimizing unnecessary IO cache usage when merging segments > > (where we really want the newly merged segments in the IO cache rather > than > > the old segment files). > > > > How would the advise method work? Would there need to be a hint in the > > FileChannel.map method? > > > > -J > > > > On Mon, Jun 15, 2009 at 12:36 AM, Alan Bateman <alan.bate...@sun.com> > wrote: > >> > >> Jason Rutherglen wrote: > >>> > >>> Is there going to be a way to do this in the new Java IO APIs? > >> > >> Good question, as it has come up a few times and is needed for some > >> important use-cases. A while back I looked into adding a > >> MappedByteBuffer#advise method to allow the application provide hints > on the > >> expected usage but didn't complete it. We should probably look at this > again > >> for jdk7. > >> > >> -Alan. > >> > > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: java-dev-unsubscr...@lucene.apache.org > For additional commands, e-mail: java-dev-h...@lucene.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: java-dev-unsubscr...@lucene.apache.org For additional commands, e-mail: java-dev-h...@lucene.apache.org
