On 6/28/2013 2:49 PM, Frank McCormick wrote: > For now I will run regular 32-bit Sid..realizing I am wasting > the opportunity to utilize more memory and perhaps faster operations.
Your 32 bit PAE Sid kernel can address 64GB. Since your new machine will have less than 64GB RAM you're wasting no opportunity. Your only limitation is 2GB per process. How many of your apps consume more than 2GB of RAM? Note that if you have an 8GB machine you can run 4 apps each consuming 2GB RAM. Something I forgot to mention previously is that a PAE kernel can use all the memory from 4GB-64GB for buffer cache. WRT speed, the vast majority of 32 bit integer programs will execute slightly faster than their 64 bit counterparts due to more efficient cache use--32 bit instructions consume less memory space than 64 bit instructions, thus more instructions fit in L1/2/3 caches. This, combined with plenty of rename registers, offsets the advantage of the extra 8 architectural registers available in long mode. 64 bit floating point Linux desktop applications likely won't be any faster because most developers aren't yet coding for SSE3/4 or AVX, but for SSE2. And SSE2 is what is used in 32 bit apps. If you do have an app that uses SSE3/4 or AVX it may be significantly faster than its 32 bit counterpart. And now the kicker. None of the above means squat if you bought a modern fast CPU with plenty of cache. There will be no perceptible difference between 32/64 bit OS platforms running the standard fare of desktop applications. To make the 64 bit platform strut its stuff you must aggressively walk very large tables that consume much more than 4GB of RAM. Things of this nature would include using 3D modeling software and doing real time 3 dimensional walk-thrus of very complex models with millions of complex parts, such as DNA chains or fighter jets. Another example would be real time pattern recognition. This is where you'll see the address translation mechanisms, both kernel code and hardware, of PAE start to fall over. You won't see it with typical desktop apps. Again, I'm not advocating that a 32 bit software platform is better than, or preferable to, a 64 bit platform. I'm simply presenting you the the facts about the differences. I agree with many others who have stated it doesn't make sense to do a fresh build today using 32 bit software. But you're not doing a fresh build. You're in the transitional phase and were looking for the easiest immediate path forward. -- Stan -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/51ce7910.8000...@hardwarefreak.com
