--- Leon Rosenberg <[EMAIL PROTECTED]> wrote: > Ok, my fault, > read "page" and "java" in one sentence -> map to Java Page -> Java > Server Page. Must be a circuit error in the brain. > Anyway, does it mean, that a proper configured JVM on an opteron > processor, will be significantly faster? Could be very interesting for > caches... > > Leon > > On 4/3/06, Rainer Jung <[EMAIL PROTECTED]> wrote: > > Using large pages to eliminate TLB misses has nothing to do with the > > size of the objects. From the view of the operating system java heap is > > just a huge and continuous chunk of memory. Anything what's inside is > > managed by the JVM. But whenever the JVM needs to access an adress it > > needs to make an address calculation as described in the article. Once > > the needed adress translation tables do not fit into the TLB, > > performance gets bad. Since Java often uses a large and continuous heap > > it's a very good candidate for using large pages, saving entries in the
Hmmm, Im not sure about this. I do agree that a page size too small will make a heavy use of CPU/OS internal structures, resulting in poor performance. OTOH, using a page size too big results in degradation of effectiveness of that processes working set. Suppose a whole block of 1 MB was out of the TLB or swapped out. Operating on a relatively small, well grouped memory region, would result in the whole 1 or 2 MB of memory be introduced into the active set, instead of just those "smaller pages". Of course, having portions of your memory collect dust, could be a sign of poor programming, memory leaks and what not. You mileage may vary. Setting a page size to 2 MB may be a bit extreme. If it can be set to just one process and dynamically, or at least at startup, that would be coll. Somehow, I doubt this level of flexibility exists. You may spead up your JVM, but slow down the rest of the system. Again, YMMV. This should be put to a test. Nix. __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
