In summary - More address space at the expense of longer addresses. No 4 gig memory cap but each gig is 'worth' slightly less.
On Tue, Sep 3, 2013 at 9:08 AM, Mark A Kruger <mkru...@cfwebtools.com>wrote: > > Michael, > > This is out of my head so forgive me if I am off on a factual point or two > - > but you will get the gist of it. > > In 32 bit addressing each memory "address" takes up 4 bytes (4 x 8 bits) > but a 64 bit address space is wider (as in 8 x 8 bits). So for example, if > you store an integer - say 14 - on a 32 bit system, it will take 4 bytes to > do it (00000000 00000000 00000000 00001110). Of course you might think > "hmmmm... it could actually store that in a single byte - but being that > draconian with storage would only slow the computer down. It needs lots of > "address spaces" of uniform size. Think of a post office with dozens of > "P.O. Boxes" - little cubbies where mail is placed. It would not make sense > for them to resize each box for the volume of mail. They just accept the > fact that some boxes have 1 letter and others may have 12 or 13. > > In a 64bit address space however the address spaces are wider (by another > 32 > bits). So that 14 is going to look like 00000000 00000000 00000000 00000000 > 00000000 00000000 00000000 00001110 internally. The advantage of 64bit is > NOT in speed of addressability. They are generally faster because they are > new gen systems with faster FSB, shorter electron paths, better L2/3 caches > etc. The advantage is in total addressability. The 32 bit system is > limited > to 2 to the 32nd power (4.2 billion add "addresses) whereas 64 bit systems > have 2 to the 64th power addresses. The "width" means exponentially more > addresses available as "PO boxes" for bits of things that need storing. > When > I say exponential I mean something like 16 exabytes of possible addressable > space. > > So the good news is that a 64 bit system can utilize an unlimited amount of > memory (unlimited in any practical sense at this point in our computer > evolution). The bad news is, it takes more room to store equivalent data. > > -Mark > > > > Mark Kruger - CFG > CF Webtools > www.cfwebtools.com > www.coldfusionmuse.com > O: 402.932.3318 > E: mkru...@cfwebtools.com > Skype: markakruger > > > > -----Original Message----- > From: Michael Dinowitz [mailto:mdino...@houseoffusion.com] > Sent: Tuesday, September 03, 2013 7:19 AM > To: cf-talk > Subject: Re: Good jvm ram settings for 64 bit ColdFusion > > > Mark, > > To start, the assignment of 6 gig to maxheap and 2 gig to maxperm is > working perfectly. > I'll expose my ignorance here and ask about that 80%. Is there some > inefficiency in jvm ram assignment in 64 bit in comparison to 32 bit? Is > there more overhead in ram assignment? Just wondering what's up with the > difference. > > Thanks > > > On Mon, Sep 2, 2013 at 2:13 PM, Mark A Kruger <mkru...@cfwebtools.com > >wrote: > > > > > Michael, > > > > Rule of thumb is 80% for equivelancy. In other words, a 1.8 gig 64bit is > > equal to a 1gig 32 bit. Heap. Or you can just multiply times 2 (which is > > usually what I do). So a 6 gig heap is roughly 3 or more times the size > of > > your 32bit 1 gig heap. If your server is dedicated to CF I think your 6 > gig > > heap is great. Takes most of the physical memory for CF and leaves 2gs > for > > the OS, monitoring etc. > > > > -Mark > > -----Original Message----- > > From: Michael Dinowitz [mailto:mdino...@houseoffusion.com] > > Sent: Monday, September 02, 2013 12:18 PM > > To: cf-talk > > Subject: Good jvm ram settings for 64 bit ColdFusion > > > > > > Does anyone have any suggestions for good workable ram settings on a 64 > bit > > CF10 install on a box with 8 gig of ram? I understand I can use more than > > the standard 1 gig but has there been any work on the best settings? > > Otherwise I'm thinking to start with 6 gig maxheap and 4 gig maxperm. > > > > > > > > > > > > > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| Order the Adobe Coldfusion Anthology now! http://www.amazon.com/Adobe-Coldfusion-Anthology/dp/1430272155/?tag=houseoffusion Archive: http://www.houseoffusion.com/groups/cf-talk/message.cfm/messageid:356697 Subscription: http://www.houseoffusion.com/groups/cf-talk/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/groups/cf-talk/unsubscribe.cfm
