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Yonik Seeley commented on LUCENE-2825: -------------------------------------- There could be a number of things that could make this very OS dependent: - kernel read-ahead can differ between mmap and traditional IO, and differ between operating systems (think about reading 10 bytes from position 4094... if mmap doesn't read-ahead at least one page then you will suffer a double page fault). - CPU cache / TLB effects? Using more address space isn't completely free. - Java mmap overhead - you don't get access to a raw byte[] - userspace-kernel transition times (i.e. for a read system call) differ between operating systems. Linux is very good here, probably leading to less of a penalty for read vs mmap. > FSDirectory.open should return MMap on 64-bit Solaris > ----------------------------------------------------- > > Key: LUCENE-2825 > URL: https://issues.apache.org/jira/browse/LUCENE-2825 > Project: Lucene - Java > Issue Type: Improvement > Components: Store > Reporter: Robert Muir > Fix For: 3.1, 4.0 > > Attachments: LUCENE-2825.patch > > > MMap is ~ 30% faster than NIOFS on this platform. -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online. --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org For additional commands, e-mail: dev-h...@lucene.apache.org