Thanks for the great info, Johan. To answer one of your questions, yes, we are running on Windows (currently a requirement).
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Johan Svensson Sent: Thursday, December 10, 2009 6:56 AM To: Neo user discussions Subject: Re: [Neo] I/O load in Neo during traversals This probably (again) has to do with OS and file system in use. If the string store is larger than assigned memory for it (see http://wiki.neo4j.org/content/Neo_Performance_Guide#Tuning_memory_mapped_I.2 FO) depending on access patterns the memory will be spread out over the store (so a read/write can be read/written to memory instead of the actual file). If you only do read operations and you start to do reads on an area of the file that has not been cached you will first start hitting the file. If requests continue to hit that area some other part of the file (that has been cached) with lower request rate will be swapped out and the free memory used for the new "hot spot". During this swap a request will be made to the system to "sync all changes in this buffer to disk" then unmap and use the free memory to memory map the new region. If no changes has been made to the buffer the OS should just release it but I have seen this is not always the case (sometimes resulting in full write out of the buffer). If you are running on Windows or have turned memory mapped buffers off the full buffer will always be written out (this can be fixed and is on my todo list). -Johan On Wed, Dec 9, 2009 at 10:56 PM, Rick Bullotta <[email protected]> wrote: > When doing some large traversal testing (no writes/updates), I noticed that > the neostore.propertystore.db.strings file was seeing a lot of read I/O (as > expected) but also a huge amount of write I/O (almost 5X the read I/O rate). > Out of curiosity, what is the write activity that needs to occur when doing > traversals? _______________________________________________ Neo mailing list [email protected] https://lists.neo4j.org/mailman/listinfo/user _______________________________________________ Neo mailing list [email protected] https://lists.neo4j.org/mailman/listinfo/user
