Comments on: 32bit vs 64bit computers, the QA http://www.alexonlinux.com/32bit-vs-64bit-computers-the-qa Sun, 05 Feb 2012 21:17:46 +0000 hourly 1 http://wordpress.org/?v= By: Andre Goddard Rosa http://www.alexonlinux.com/32bit-vs-64bit-computers-the-qa/comment-page-1#comment-23395 Andre Goddard Rosa Mon, 27 Jul 2009 19:17:13 +0000 http://www.alexandersandler.net/?page_id=376#comment-23395 <a href='#comment-22544' rel="nofollow">@David Brown</a> - Thanks again for your helpful insights!<div class="comment-remix-meta"><a href="#" class="replyto" onclick="replyto('23395','Andre Goddard Rosa'); return false;">Reply</a> - <a href="#" class="quote" onclick="quote('23395','Andre Goddard Rosa','<a href=\'#comment-22544\' rel=\"nofollow\">@David Brown<\/a> - Thanks again for your helpful insights!'); return false;">Quote</a></div> @David Brown – Thanks again for your helpful insights!
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]]> By: David Brown http://www.alexonlinux.com/32bit-vs-64bit-computers-the-qa/comment-page-1#comment-22544 David Brown Mon, 25 May 2009 08:26:26 +0000 http://www.alexandersandler.net/?page_id=376#comment-22544 There seems to be a bit of mixup about physical memory limits and address space limits. With a 32-bit processor, you have a maximum linear address space of 4GB. Different OS's can place other limits on these, such as making 1GB or 2GB of this "kernel" address space, leaving 3GB or 2GB for "user" address space. These limitations are at the logical level, and are per-process. They apply to the whole virtual address space (your physical memory, plus swap space). Intel PAE allows a 32-bit processor to have more than 4GB physical ram (without PAE, you can get more than 4GB virtual memory if you have swap space). PAE requires support from the motherboard and from the OS. Windows "server" editions typically have PAE enabled, as do "server" kernels for Linux. However, PAE adds overhead to normal access, so don't use it unless you need it. It also does not affect the maximum address space accessible per process - a single process cannot directly access more than 4GB space even if you have 32GB physical ram. Also, part of the physical address space is eaten up by PCI and other memory-mapped peripherals. Thus with a 32-bit processor/OS and no PAE, you get a maximum of about 3.2 GB physical memory (details depend on the hardware). With a 64-bit processor and OS, your physical memory limits are dependent on the motherboard and processor, and any artificial limits imposed by the OS. The per-process logical address space is unlikely to be a bottleneck with 64-bit addresses! As a general rule, you want a 32-bit OS for 2GB or less, and a 64-bit OS for 4GB or more. For modern systems, there is no reason for using PAE to get more memory in a 32-bit system. If you are using Linux and using mainly open-source software, you can happily use 64-bit for everything, even if you have less memory - pretty much all software will work at 64-bit. Some software will be faster (taking advantage of the additional registers, and perhaps 64-bit arithmetic), some will be slower (due mainly to larger pointers taking more memory). 32-bit binary-only software, such as flash plugins and media codecs, have traditionally been a problem for 64-bit Linux systems, but support has improved greatly. For Windows, the situation is different - there can be many unexpected compatibility problems with using 64-bit windows. There are (so I've heard) fewer issues with Vista 64 (in the sense that if a program is incompatible with Vista 64, it is probably also incompatible with Vista 32), but XP 64 had problems with a lot of software. And of course, you have endless fun with 32-bit drivers and unsigned drivers not working on Vista 64.<div class="comment-remix-meta"><a href="#" class="replyto" onclick="replyto('22544','David Brown'); return false;">Reply</a> - <a href="#" class="quote" onclick="quote('22544','David Brown','There seems to be a bit of mixup about physical memory limits and address space limits. With a 32-bit processor, you have a maximum linear address space of 4GB. Different OS\'s can place other limits on these, such as making 1GB or 2GB of this \"kernel\" address space, leaving 3GB or 2GB for \"user\" address space. These limitations are at the logical level, and are per-process. They apply to the whole virtual address space (your physical memory, plus swap space).\r\n\r\nIntel PAE allows a 32-bit processor to have more than 4GB physical ram (without PAE, you can get more than 4GB virtual memory if you have swap space). PAE requires support from the motherboard and from the OS. Windows \"server\" editions typically have PAE enabled, as do \"server\" kernels for Linux. However, PAE adds overhead to normal access, so don\'t use it unless you need it. It also does not affect the maximum address space accessible per process - a single process cannot directly access more than 4GB space even if you have 32GB physical ram.\r\n\r\nAlso, part of the physical address space is eaten up by PCI and other memory-mapped peripherals. Thus with a 32-bit processor\/OS and no PAE, you get a maximum of about 3.2 GB physical memory (details depend on the hardware).\r\n\r\nWith a 64-bit processor and OS, your physical memory limits are dependent on the motherboard and processor, and any artificial limits imposed by the OS. The per-process logical address space is unlikely to be a bottleneck with 64-bit addresses!\r\n\r\nAs a general rule, you want a 32-bit OS for 2GB or less, and a 64-bit OS for 4GB or more. For modern systems, there is no reason for using PAE to get more memory in a 32-bit system. \r\n\r\nIf you are using Linux and using mainly open-source software, you can happily use 64-bit for everything, even if you have less memory - pretty much all software will work at 64-bit. Some software will be faster (taking advantage of the additional registers, and perhaps 64-bit arithmetic), some will be slower (due mainly to larger pointers taking more memory). 32-bit binary-only software, such as flash plugins and media codecs, have traditionally been a problem for 64-bit Linux systems, but support has improved greatly.\r\n\r\nFor Windows, the situation is different - there can be many unexpected compatibility problems with using 64-bit windows. There are (so I\'ve heard) fewer issues with Vista 64 (in the sense that if a program is incompatible with Vista 64, it is probably also incompatible with Vista 32), but XP 64 had problems with a lot of software. And of course, you have endless fun with 32-bit drivers and unsigned drivers not working on Vista 64.'); return false;">Quote</a></div> There seems to be a bit of mixup about physical memory limits and address space limits. With a 32-bit processor, you have a maximum linear address space of 4GB. Different OS’s can place other limits on these, such as making 1GB or 2GB of this “kernel” address space, leaving 3GB or 2GB for “user” address space. These limitations are at the logical level, and are per-process. They apply to the whole virtual address space (your physical memory, plus swap space).

Intel PAE allows a 32-bit processor to have more than 4GB physical ram (without PAE, you can get more than 4GB virtual memory if you have swap space). PAE requires support from the motherboard and from the OS. Windows “server” editions typically have PAE enabled, as do “server” kernels for Linux. However, PAE adds overhead to normal access, so don’t use it unless you need it. It also does not affect the maximum address space accessible per process – a single process cannot directly access more than 4GB space even if you have 32GB physical ram.

Also, part of the physical address space is eaten up by PCI and other memory-mapped peripherals. Thus with a 32-bit processor/OS and no PAE, you get a maximum of about 3.2 GB physical memory (details depend on the hardware).

With a 64-bit processor and OS, your physical memory limits are dependent on the motherboard and processor, and any artificial limits imposed by the OS. The per-process logical address space is unlikely to be a bottleneck with 64-bit addresses!

As a general rule, you want a 32-bit OS for 2GB or less, and a 64-bit OS for 4GB or more. For modern systems, there is no reason for using PAE to get more memory in a 32-bit system.

If you are using Linux and using mainly open-source software, you can happily use 64-bit for everything, even if you have less memory – pretty much all software will work at 64-bit. Some software will be faster (taking advantage of the additional registers, and perhaps 64-bit arithmetic), some will be slower (due mainly to larger pointers taking more memory). 32-bit binary-only software, such as flash plugins and media codecs, have traditionally been a problem for 64-bit Linux systems, but support has improved greatly.

For Windows, the situation is different – there can be many unexpected compatibility problems with using 64-bit windows. There are (so I’ve heard) fewer issues with Vista 64 (in the sense that if a program is incompatible with Vista 64, it is probably also incompatible with Vista 32), but XP 64 had problems with a lot of software. And of course, you have endless fun with 32-bit drivers and unsigned drivers not working on Vista 64.

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]]> By: Alexander Sandler http://www.alexonlinux.com/32bit-vs-64bit-computers-the-qa/comment-page-1#comment-14033 Alexander Sandler Wed, 22 Oct 2008 08:38:08 +0000 http://www.alexandersandler.net/?page_id=376#comment-14033 <a href='#comment-13848' rel="nofollow">@Somanie</a> It is a little strange because it contradicts with <a href="http://msdn.microsoft.com/en-us/library/aa366778.aspx" rel="nofollow">this article on MSDN</a>.<div class="comment-remix-meta"><a href="#" class="replyto" onclick="replyto('14033','Alexander Sandler'); return false;">Reply</a> - <a href="#" class="quote" onclick="quote('14033','Alexander Sandler','<a href=\'#comment-13848\' rel=\"nofollow\">@Somanie<\/a>\r\nIt is a little strange because it contradicts with <a href=\"http:\/\/msdn.microsoft.com\/en-us\/library\/aa366778.aspx\" rel=\"nofollow\">this article on MSDN<\/a>.'); return false;">Quote</a></div> @Somanie
It is a little strange because it contradicts with this article on MSDN.
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]]> By: Somanie http://www.alexonlinux.com/32bit-vs-64bit-computers-the-qa/comment-page-1#comment-13848 Somanie Thu, 16 Oct 2008 04:47:02 +0000 http://www.alexandersandler.net/?page_id=376#comment-13848 @ John L. Galt: You DON'T need 64-bit to run more than 4GB of RAM. I'm currently running 16GB of RAM in a Windows Vista Ultimate 32-bit OS. My MB support up to 16GB of RAM and so did the CPUs (Dual Xeon 3.0GHz) and my 32-bit OS recognizes all the available RAM. So, NO, you don't need 64-bit to run more than 4GB of RAM, you need a MB that can handle it.<div class="comment-remix-meta"><a href="#" class="replyto" onclick="replyto('13848','Somanie'); return false;">Reply</a> - <a href="#" class="quote" onclick="quote('13848','Somanie','@ John L. Galt: You DON\'T need 64-bit to run more than 4GB of RAM. I\'m currently running 16GB of RAM in a Windows Vista Ultimate 32-bit OS. My MB support up to 16GB of RAM and so did the CPUs (Dual Xeon 3.0GHz) and my 32-bit OS recognizes all the available RAM. So, NO, you don\'t need 64-bit to run more than 4GB of RAM, you need a MB that can handle it.'); return false;">Quote</a></div> @ John L. Galt: You DON’T need 64-bit to run more than 4GB of RAM. I’m currently running 16GB of RAM in a Windows Vista Ultimate 32-bit OS. My MB support up to 16GB of RAM and so did the CPUs (Dual Xeon 3.0GHz) and my 32-bit OS recognizes all the available RAM. So, NO, you don’t need 64-bit to run more than 4GB of RAM, you need a MB that can handle it.
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]]> By: Alexander Sandler http://www.alexonlinux.com/32bit-vs-64bit-computers-the-qa/comment-page-1#comment-11222 Alexander Sandler Thu, 28 Aug 2008 08:07:58 +0000 http://www.alexandersandler.net/?page_id=376#comment-11222 @rasmasyean: I am not sure I got your SolidWorks argument - SolidWorks is not your average home application. However, you're right. It seems that both 32-bit XP and 32-bit Vista limit amount of supported physical memory to 4GB (another good reason to switch to Linux :D ). So at the end amount of RAM is a consideration when deciding between 32-bit and 64-bit Windows - I'll update the article to reflect this. Thanks for your notes.<div class="comment-remix-meta"><a href="#" class="replyto" onclick="replyto('11222','Alexander Sandler'); return false;">Reply</a> - <a href="#" class="quote" onclick="quote('11222','Alexander Sandler','@rasmasyean: I am not sure I got your SolidWorks argument - SolidWorks is not your average home application. \r\nHowever, you\'re right. It seems that both 32-bit XP and 32-bit Vista limit amount of supported physical memory to 4GB (another good reason to switch to Linux :D ). So at the end amount of RAM is a consideration when deciding between 32-bit and 64-bit Windows - I\'ll update the article to reflect this. Thanks for your notes.'); return false;">Quote</a></div> @rasmasyean: I am not sure I got your SolidWorks argument – SolidWorks is not your average home application.
However, you’re right. It seems that both 32-bit XP and 32-bit Vista limit amount of supported physical memory to 4GB (another good reason to switch to Linux :D ). So at the end amount of RAM is a consideration when deciding between 32-bit and 64-bit Windows – I’ll update the article to reflect this. Thanks for your notes.
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]]> By: Alexander Sandler http://www.alexonlinux.com/32bit-vs-64bit-computers-the-qa/comment-page-1#comment-11221 Alexander Sandler Thu, 28 Aug 2008 08:04:27 +0000 http://www.alexandersandler.net/?page_id=376#comment-11221 @John L. Galt: Well... There are not many 16-bit applications left, but you're right, lack of 64-bit drivers may become a serious problem.<div class="comment-remix-meta"><a href="#" class="replyto" onclick="replyto('11221','Alexander Sandler'); return false;">Reply</a> - <a href="#" class="quote" onclick="quote('11221','Alexander Sandler','@John L. Galt: Well... There are not many 16-bit applications left, but you\'re right, lack of 64-bit drivers may become a serious problem.'); return false;">Quote</a></div> @John L. Galt: Well… There are not many 16-bit applications left, but you’re right, lack of 64-bit drivers may become a serious problem.
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]]> By: Alexander Sandler http://www.alexonlinux.com/32bit-vs-64bit-computers-the-qa/comment-page-1#comment-11220 Alexander Sandler Thu, 28 Aug 2008 08:02:07 +0000 http://www.alexandersandler.net/?page_id=376#comment-11220 @John L. Galt: You can access more than 4GB with two processes. This is why this is virtual memory. You're right. Today more and more vendors create 64-bit versions of their software. So in couple of years having 64-bit OS may become worthwhile.<div class="comment-remix-meta"><a href="#" class="replyto" onclick="replyto('11220','Alexander Sandler'); return false;">Reply</a> - <a href="#" class="quote" onclick="quote('11220','Alexander Sandler','@John L. Galt: You can access more than 4GB with two processes. This is why this is virtual memory.\r\nYou\'re right. Today more and more vendors create 64-bit versions of their software. So in couple of years having 64-bit OS may become worthwhile.'); return false;">Quote</a></div> @John L. Galt: You can access more than 4GB with two processes. This is why this is virtual memory.
You’re right. Today more and more vendors create 64-bit versions of their software. So in couple of years having 64-bit OS may become worthwhile.
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]]> By: John L. Galt http://www.alexonlinux.com/32bit-vs-64bit-computers-the-qa/comment-page-1#comment-11218 John L. Galt Thu, 28 Aug 2008 07:45:49 +0000 http://www.alexandersandler.net/?page_id=376#comment-11218 Actually, the only reason I cansee not ot go to 64bit OSs is if you ahve legacy 16bit or even (shudder!) 8bit apps that need to run, or legacy hardware that has no 64bit drivers.<div class="comment-remix-meta"><a href="#" class="replyto" onclick="replyto('11218','John L. Galt'); return false;">Reply</a> - <a href="#" class="quote" onclick="quote('11218','John L. Galt','Actually, the only reason I cansee not ot go to 64bit OSs is if you ahve legacy 16bit or even (shudder!) 8bit apps that need to run, or legacy hardware that has no 64bit drivers.'); return false;">Quote</a></div> Actually, the only reason I cansee not ot go to 64bit OSs is if you ahve legacy 16bit or even (shudder!) 8bit apps that need to run, or legacy hardware that has no 64bit drivers.
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]]> By: John L. Galt http://www.alexonlinux.com/32bit-vs-64bit-computers-the-qa/comment-page-1#comment-11213 John L. Galt Thu, 28 Aug 2008 03:49:15 +0000 http://www.alexandersandler.net/?page_id=376#comment-11213 “update: That’s not true. If your hardware supports more than 4GB, there is no reason to buy 64-bit Windows. 32-bit XP supports 4GB+. So it was right not to mention this because in terms of bitness it does not matter how much RAM you have. If your hardware does not support more than 4GB, then 64-bit OS won’t help you anyway.”

Sorry, do the math.

2^32 = 4 GB. 32bit applications cannot access more than 4 GB of RAM.

Also, there are a few programs that can be recompiled for 64bit OS, especially open-source programs (as you have already noted) as well as others, provided a person has the know how and wherewithal to do so. Finally, The next version of Photoshop is going 64bit, just to name *one* prominent application.

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]]> By: rasmasyean http://www.alexonlinux.com/32bit-vs-64bit-computers-the-qa/comment-page-1#comment-11210 rasmasyean Thu, 28 Aug 2008 01:25:05 +0000 http://www.alexandersandler.net/?page_id=376#comment-11210 You mean with PAE? http://en.wikipedia.org/wiki/Physical_Address_Extension That is true, but to my understanding, this is usually for servers so I guess it depends on your budget or application. But that still doesn't seem to allow you as much as this... "...all 64-bit versions of Microsoft operating systems currently impose a 16 TB limit on address space and allow no more than 128 GB of physical memory due to the impracticality of having 16 TB of RAM. Processes created on Windows Vista x64 Edition are allotted 8 TB in virtual memory for user processes and 8 TB for kernel processes to create a virtual memory of 16 TB." http://zone.ni.com/devzone/cda/tut/p/id/5709 Here is an application. http://www.youtube.com/watch?v=PDOf3IEr4FU<div class="comment-remix-meta"><a href="#" class="replyto" onclick="replyto('11210','rasmasyean'); return false;">Reply</a> - <a href="#" class="quote" onclick="quote('11210','rasmasyean','You mean with PAE?\r\nhttp:\/\/en.wikipedia.org\/wiki\/Physical_Address_Extension\r\n\r\nThat is true, but to my understanding, this is usually for servers so I guess it depends on your budget or application.\r\n\r\nBut that still doesn\'t seem to allow you as much as this...\r\n\"...all 64-bit versions of Microsoft operating systems currently impose a 16 TB limit on address space and allow no more than 128 GB of physical memory due to the impracticality of having 16 TB of RAM. Processes created on Windows Vista x64 Edition are allotted 8 TB in virtual memory for user processes and 8 TB for kernel processes to create a virtual memory of 16 TB.\"\r\nhttp:\/\/zone.ni.com\/devzone\/cda\/tut\/p\/id\/5709\r\n\r\nHere is an application.\r\nhttp:\/\/www.youtube.com\/watch?v=PDOf3IEr4FU'); return false;">Quote</a></div> You mean with PAE?
http://en.wikipedia.org/wiki/Physical_Address_Extension

That is true, but to my understanding, this is usually for servers so I guess it depends on your budget or application.

But that still doesn’t seem to allow you as much as this…
“…all 64-bit versions of Microsoft operating systems currently impose a 16 TB limit on address space and allow no more than 128 GB of physical memory due to the impracticality of having 16 TB of RAM. Processes created on Windows Vista x64 Edition are allotted 8 TB in virtual memory for user processes and 8 TB for kernel processes to create a virtual memory of 16 TB.”
http://zone.ni.com/devzone/cda/tut/p/id/5709

Here is an application.
http://www.youtube.com/watch?v=PDOf3IEr4FU

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