Re: Debian Lenny 32
On 12/30/2011 8:59 AM, Camaleón wrote: On Thu, 29 Dec 2011 21:32:06 -0600, Stan Hoeppner wrote: On 12/29/2011 10:53 AM, Camaleón wrote: On Thu, 29 Dec 2011 18:26:28 +0200, Mohamed Daif wrote: What is the maximum RAM supported in Debian Lenny 32bit . It should be 64 GiB with a PAE enabled kernel (bigmem). 64GB max for the kernel, but userspace processes are still limited to a 4GB virtual address space. Thus if one has an application, say a database or medical imaging app (think MRI), that requires direct access to say, 32GB of RAM, one should be using an x86-64 kernel and an application compiled for an x86-64 target. That's a self-imposed limitation. It could be by-passed by using memory mapping techniques (this is documented in the wikipedia page you pointed out about PAE, which specifically mentions mmap()) but not many linux applications are making use of it, I'm afraid, contrary what happens on Windows systems. In the end, applications that need to handle/move big quantities of data directly from the RAM will benefit of a pure 64-bits OS. Mostly correct. Using mmap() to get access to all that extra memory still has significant limitations. Note that 64 bit Linux has been around long enough that there was no motivation for anyone to write a convoluted large memory application for 32 bit x86 PAE systems. 64 bit Linux has been running on Alpha and SPARC since the late '90s, both platforms offering up to 8GB on workstation hardware and 128GB on servers, with native 64 bit flat addressing. 64 bit Itanium systems hit the market in the early 2000s with most workstations offering 16GB of RAM and servers offering up to 1TB. Thus, anyone serious about writing an app that needed more than a direct 4GB address space was doing it on non-x86 hardware, of which there was plenty. x86-64 arrived around the same time as IA-64, putting the nail in the large memory x86 coffin, from an application developer standpoint. Worth noting is that to date, AFAIK, the only mainstream Windows applications ever written that take good advantage of PAE are MSSQL server and Win32 Oracle. I'd love to hear of other examples, if there are any. -- 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/4efecaae.7050...@hardwarefreak.com
Re: Debian Lenny 32
On Fri, 30 Dec 2011 12:25:21 -0700, Bob Proulx wrote: Camaleón wrote: Stan Hoeppner wrote: Camaleón wrote: Mohamed Daif wrote: What is the maximum RAM supported in Debian Lenny 32bit . It should be 64 GiB with a PAE enabled kernel (bigmem). 64GB max for the kernel, but userspace processes are still limited to a 4GB virtual address space. Thus if one has an application, say a database or medical imaging app (think MRI), that requires direct access to say, 32GB of RAM, one should be using an x86-64 kernel and an application compiled for an x86-64 target. That's a self-imposed limitation. What is self-imposed? 4GB of virtual address space? That is the definition of a 32-bit address space. It is only self imposed if you include choosing a 32-bit architecture in the choice. And actually unless you do special things you really will be limited to 3G. (It used to be that you couldn't get above 2G without linking with -N. But things have been rewritten to make 3G the default now.) Going to 64-bits is the much easier way to make use of a large memory space. Yes, I do know. It can be still useful under determined scenarios to be able to map as much ram as you can, i.e., for databases. It could be by-passed by using memory mapping techniques (this is documented in the wikipedia page you pointed out about PAE, which specifically mentions mmap()) but not many linux applications are making use of it, I'm afraid, contrary what happens on Windows systems. None of that is real memory. Even if an application codes in the ability to use application level paging to handle more data the program itself is still limited to 32-bits. That's what memory mapping is for and that's what PAE does at a different level. Being convenient or not, being real or virtual it's an option for 32-bits systems that need to handle big amounts of data, system wide or per-process. (There are a lot of wonderful Seymour Cray quotes, or at least attributions to him even if he didn't actually say them, that I really wanted to say here about memory. Consider this an in joke for everyone who knows what I am talking about. I will leave with this one: Virtual memory leads to virtual performance.) I personally don't like how PAE nor mmap() do they work. They are by- passes, patches but not a real solution to the problem. Yes, there are noticeable penalties for a system starting from 8 GiB of RAM when using PAE (this was discussed on the kernel mailing lists a year or so ago), but I'm not judging if this (PAE, mmap...) is convenient or not just point there are ways to remove the 4 GiB pero process restriction. Whether this is optimal or not is another issue. In the end, applications that need to handle/move big quantities of data directly from the RAM will benefit of a pure 64-bits OS. Agreed. But I don't think we have gotten to the point where most desktop users need it yet. *Wanting* it is fine though. But even most people's pig applications of libreoffice and firefox don't usually need more than 3G of memory. But of course if there is any application (usually scientific or some other technical domain) that needs more than 3G of data space then they really do need a 64-bit architecture. They usually already know who they are. Yes, I do also think so. Infact, I've got the impression we do not either need such powerful systems for evey user and every mundane task, a Pentium III is still perfect capable of doing 70% of a default user dayly work :-) But one of the pros of encouraging people to jump to 64-bits based applications/OSes is that programmers and developers had to do the coding work to adapt the programs to the 64-bits arquitecture and now there not many applications that cannot be run on the new platform. There is always side benefits... Greetings, -- Camaleón -- 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/pan.2011.12.31.10.39...@gmail.com
Re: Debian Lenny 32
On Thu, 29 Dec 2011 21:32:06 -0600, Stan Hoeppner wrote: On 12/29/2011 10:53 AM, Camaleón wrote: On Thu, 29 Dec 2011 18:26:28 +0200, Mohamed Daif wrote: What is the maximum RAM supported in Debian Lenny 32bit . It should be 64 GiB with a PAE enabled kernel (bigmem). 64GB max for the kernel, but userspace processes are still limited to a 4GB virtual address space. Thus if one has an application, say a database or medical imaging app (think MRI), that requires direct access to say, 32GB of RAM, one should be using an x86-64 kernel and an application compiled for an x86-64 target. That's a self-imposed limitation. It could be by-passed by using memory mapping techniques (this is documented in the wikipedia page you pointed out about PAE, which specifically mentions mmap()) but not many linux applications are making use of it, I'm afraid, contrary what happens on Windows systems. In the end, applications that need to handle/move big quantities of data directly from the RAM will benefit of a pure 64-bits OS. Greetings, -- Camaleón -- 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/pan.2011.12.30.14.59...@gmail.com
Re: Debian Lenny 32
On Thu, 29 Dec 2011 18:37:41 -0500, Charles Kroeger wrote: On Thu, 29 Dec 2011 17:50:02 +0100 Mohamed Daif mohamed.d...@gmail.com wrote: Hello What is the maximum RAM supported in Debian Lenny 32bit . Doesn't the motherboard have something to do with that? Well, sort of. Technically speaking there can be many things that limit in some way the available/addressable amount of RAM: motherboard, BIOS version, different combo of RAM layouts, operating system (e.g., the different windows flavours impose cosmetic license based limitations for home/ professional/server editions), operating system bugs... Greetings, -- Camaleón -- 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/pan.2011.12.30.17.02...@gmail.com
Re: Debian Lenny 32
Camaleón wrote: Stan Hoeppner wrote: Camaleón wrote: Mohamed Daif wrote: What is the maximum RAM supported in Debian Lenny 32bit . It should be 64 GiB with a PAE enabled kernel (bigmem). 64GB max for the kernel, but userspace processes are still limited to a 4GB virtual address space. Thus if one has an application, say a database or medical imaging app (think MRI), that requires direct access to say, 32GB of RAM, one should be using an x86-64 kernel and an application compiled for an x86-64 target. That's a self-imposed limitation. What is self-imposed? 4GB of virtual address space? That is the definition of a 32-bit address space. It is only self imposed if you include choosing a 32-bit architecture in the choice. And actually unless you do special things you really will be limited to 3G. (It used to be that you couldn't get above 2G without linking with -N. But things have been rewritten to make 3G the default now.) Going to 64-bits is the much easier way to make use of a large memory space. It could be by-passed by using memory mapping techniques (this is documented in the wikipedia page you pointed out about PAE, which specifically mentions mmap()) but not many linux applications are making use of it, I'm afraid, contrary what happens on Windows systems. None of that is real memory. Even if an application codes in the ability to use application level paging to handle more data the program itself is still limited to 32-bits. (There are a lot of wonderful Seymour Cray quotes, or at least attributions to him even if he didn't actually say them, that I really wanted to say here about memory. Consider this an in joke for everyone who knows what I am talking about. I will leave with this one: Virtual memory leads to virtual performance.) In the end, applications that need to handle/move big quantities of data directly from the RAM will benefit of a pure 64-bits OS. Agreed. But I don't think we have gotten to the point where most desktop users need it yet. *Wanting* it is fine though. But even most people's pig applications of libreoffice and firefox don't usually need more than 3G of memory. But of course if there is any application (usually scientific or some other technical domain) that needs more than 3G of data space then they really do need a 64-bit architecture. They usually already know who they are. Bob signature.asc Description: Digital signature
Re: Debian Lenny 32
Hello What is the maximum RAM supported in Debian Lenny 32bit . -- *Best Regards Mohamed Daif*
Re: Debian Lenny 32
On Thu, 29 Dec 2011 18:26:28 +0200, Mohamed Daif wrote: What is the maximum RAM supported in Debian Lenny 32bit . It should be 64 GiB with a PAE enabled kernel (bigmem). Greetings, -- Camaleón -- 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/pan.2011.12.29.16.53...@gmail.com
Re: Debian Lenny 32
On Thu, 29 Dec 2011 17:50:02 +0100 Mohamed Daif mohamed.d...@gmail.com wrote: Hello What is the maximum RAM supported in Debian Lenny 32bit . Doesn't the motherboard have something to do with that? -- CK -- 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/9m4bv4fra...@mid.individual.net
Re: Debian Lenny 32
On 12/29/2011 10:53 AM, Camaleón wrote: On Thu, 29 Dec 2011 18:26:28 +0200, Mohamed Daif wrote: What is the maximum RAM supported in Debian Lenny 32bit . It should be 64 GiB with a PAE enabled kernel (bigmem). 64GB max for the kernel, but userspace processes are still limited to a 4GB virtual address space. Thus if one has an application, say a database or medical imaging app (think MRI), that requires direct access to say, 32GB of RAM, one should be using an x86-64 kernel and an application compiled for an x86-64 target. -- 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/4efd30b6@hardwarefreak.com
Re: Debian Lenny 32
On 12/29/2011 5:37 PM, Charles Kroeger wrote: On Thu, 29 Dec 2011 17:50:02 +0100 Mohamed Daif mohamed.d...@gmail.com wrote: What is the maximum RAM supported in Debian Lenny 32bit . Doesn't the motherboard have something to do with that? No. It's a fixed 64GB limitation, due to Intel's PAE having 36 physical address bits. The limitation is PAE itself and is platform independent, assuming the platform is PPro or later, not some ancient junk nobody still uses. http://en.wikipedia.org/wiki/Physical_Address_Extension -- 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/4efd3633.2060...@hardwarefreak.com
