Re: [gentoo-user] which -march flag to pick for Intel Core 2 Duo in make.conf?
On Fri, 25 May 2007 14:26:32 -0400 Denis [EMAIL PROTECTED] wrote: On 5/25/07, Andreas Claesson [EMAIL PROTECTED] wrote: Since you (Denis) are doing a lot of mathematical calculations you will probably benefit from running in 64bit mode. I often need to run Monte Carlo simulations (in C) which involve a lot of array storage and array scanning/searching operations... I wonder what the speed-up would be for those simulations if run under a 64-bit mode. Are there any requirements on how the simulations should be programmed in order to take advantage of the 64-bit arch, or is that automatically done by the GCC compiler and the kernel? Would you mind telling us what kind of performance difference you experience? -- [EMAIL PROTECTED] mailing list
Re: [gentoo-user] which -march flag to pick for Intel Core 2 Duo in make.conf?
Denis wrote: I often need to run Monte Carlo simulations (in C) which involve a lot of array storage and array scanning/searching operations... I wonder what the speed-up would be for those simulations if run under a 64-bit mode. Are there any requirements on how the simulations should be programmed in order to take advantage of the 64-bit arch, or is that automatically done by the GCC compiler and the kernel? Just use the -m64 flag when you compile using gcc. R -- [EMAIL PROTECTED] mailing list
Re: [gentoo-user] which -march flag to pick for Intel Core 2 Duo in make.conf?
On Thu, May 24, 2007 12:38 pm, Denis wrote: My aim is to build a fast, stable system for my computations, which ultimately brought me to another major decision: 32-bit or 64-bit... I run simulations which I write in C and numerical computations which I run in Mathematica (which has just released the 64-bit version). Would a 64-bit system significantly benefit these applications? If you are using a lot of memory in your computations, then the 64-bit environment will be much friendlier to you :) Also, if I understand correctly, you will get higher precision on floating point calculations (someone correct me if I am wrong here!) I also believe that the 64 bit processors are able to perform more instructions per second on average when executing 64 bit code vs. 32 bit code if I am not mistaken... -- Randy Barlow http://www.electronsweatshop.com Oh me of little faith... -- [EMAIL PROTECTED] mailing list
RE: [gentoo-user] which -march flag to pick for Intel Core 2 Duo in make.conf?
-Original Message- From: Randy Barlow [mailto:[EMAIL PROTECTED] Sent: Friday, May 25, 2007 4:23 PM To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] which -march flag to pick for Intel Core 2 Duo in make.conf? Snip If you are using a lot of memory in your computations, then the 64-bit environment will be much friendlier to you :) Also, if I understand correctly, you will get higher precision on floating point calculations (someone correct me if I am wrong here!) I also believe that the 64 bit processors are able to perform more instructions per second on average when executing 64 bit code vs. 32 bit code if I am not mistaken... I am not sure, but that makes sense. If nothing else, things executed directly usually run more smoothly than those who are run through emulation. 64bit code on 64bit processor good... ^_^ -- [EMAIL PROTECTED] mailing list
Re: [gentoo-user] which -march flag to pick for Intel Core 2 Duo in make.conf?
On 5/25/07, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: -Original Message- From: Randy Barlow [mailto:[EMAIL PROTECTED] Snip If you are using a lot of memory in your computations, then the 64-bit environment will be much friendlier to you :) Also, if I understand correctly, you will get higher precision on floating point calculations (someone correct me if I am wrong here!) I also believe that the 64 bit processors are able to perform more instructions per second on average when executing 64 bit code vs. 32 bit code if I am not mistaken... I am not sure, but that makes sense. If nothing else, things executed directly usually run more smoothly than those who are run through emulation. 64bit code on 64bit processor good... There is no emulation involved when running 32bit code in either core2 nor amd64 processors. The difference when running in 32bit mode is that some instructions are unavailable, you have a smaller number of registers, and the registers are only 32bit. More registers speed up most kind of code, 64bit registers speed up 64bit calculations, and the extra instructions are good for array calculations and similar (more sse instructions for example). The only bad thing with 64bit code is that the programs get bigger, which may effect memory performance negatively. But if you have a lot of memory then you will benefit from not needing any special addressing modes. Since you (Denis) are doing a lot of mathematical calculations you will probably benefit from running in 64bit mode. -- [EMAIL PROTECTED] mailing list
Re: [gentoo-user] which -march flag to pick for Intel Core 2 Duo in make.conf?
On 5/25/07, Andreas Claesson [EMAIL PROTECTED] wrote: Since you (Denis) are doing a lot of mathematical calculations you will probably benefit from running in 64bit mode. I often need to run Monte Carlo simulations (in C) which involve a lot of array storage and array scanning/searching operations... I wonder what the speed-up would be for those simulations if run under a 64-bit mode. Are there any requirements on how the simulations should be programmed in order to take advantage of the 64-bit arch, or is that automatically done by the GCC compiler and the kernel? -- [EMAIL PROTECTED] mailing list
[gentoo-user] which -march flag to pick for Intel Core 2 Duo in make.conf?
Are these any options in the kernel and in the gcc to optimize for Intel's Core 2 Duo chips? When I set up my gentoo box for the Pentium Processor Extreme Edition (dual core prescott), I just used -march=prescott in make.conf Which -march flag would be the most relevant gcc optimization for Intel Core 2 Duo? And is there explicit support in the latest gentoo kernel for Core 2 Duo, or does it go under Pentium 4 family? Thanks -- [EMAIL PROTECTED] mailing list
Re: [gentoo-user] which -march flag to pick for Intel Core 2 Duo in make.conf?
On 5/24/07, Denis [EMAIL PROTECTED] wrote: Are these any options in the kernel and in the gcc to optimize for Intel's Core 2 Duo chips? When I set up my gentoo box for the Pentium Processor Extreme Edition (dual core prescott), I just used -march=prescott in make.conf Which -march flag would be the most relevant gcc optimization for Intel Core 2 Duo? And is there explicit support in the latest gentoo kernel for Core 2 Duo, or does it go under Pentium 4 family? Google is your friend: http://www.google.com/search?q=core+2+duo+cflags http://gentoo-wiki.com/Safe_Cflags#Intel_Core_2_Duo.2FQuad_.2F_Xeon_51xx.2F53xx -- Ryan W Sims -- [EMAIL PROTECTED] mailing list
Re: [gentoo-user] which -march flag to pick for Intel Core 2 Duo in make.conf?
On 5/24/07, Denis [EMAIL PROTECTED] wrote: Are these any options in the kernel and in the gcc to optimize for Intel's Core 2 Duo chips? When I set up my gentoo box for the Pentium Processor Extreme Edition (dual core prescott), I just used -march=prescott in make.conf Which -march flag would be the most relevant gcc optimization for Intel Core 2 Duo? And is there explicit support in the latest gentoo kernel for Core 2 Duo, or does it go under Pentium 4 family? Thanks -- [EMAIL PROTECTED] mailing list A gentoo forum thread[1] states to use -march=nocona for Core 2 Duo, and -march=prescott for Core Solo/Duo. [1] http://forums.gentoo.org/viewtopic-p-3602555.html -- - Mark Shields
Re: [gentoo-user] which -march flag to pick for Intel Core 2 Duo in make.conf?
After reading some docs, the impression I get is that the 'nocona' flag is for building a 64-bit system... For a 32-bit system, it seems like 'prescott' would be the choice, wouldn't it? This from the GCC website about 4.2.0 release changes: IA-32/x86-64 * -mtune=generic can now be used to generate code running well on common x86 chips. This includes AMD Athlon, AMD Opteron, Intel Pentium-M, Intel Pentium 4 and Intel Core 2. * -mtune=native and -march=native will produce code optimized for the host architecture as detected using the cpuid instruction. * Added a new command line option -fstackrealign and and __attribute__ ((force_align_arg_pointer)) to realign the stack at runtime. This allows functions compiled with a vector-aligned stack to be invoked from legacy objects that keep only word-alignment. We don't have gcc-4.2.0 in our portage available for installation yet, do we? Anyone know when? -- [EMAIL PROTECTED] mailing list
Re: [gentoo-user] which -march flag to pick for Intel Core 2 Duo in make.conf?
On Thu, 24 May 2007 11:13:30 -0400, Denis wrote: After reading some docs, the impression I get is that the 'nocona' flag is for building a 64-bit system... For a 32-bit system, it seems like 'prescott' would be the choice, wouldn't it? Yes. We don't have gcc-4.2.0 in our portage available for installation yet, do we? Anyone know when? When the devs consider it suitable for at least the testing branch or when you do echo =sys-devel/gcc-4.2* /etc/portage/package.mask, whichever comes sooner. Bear in mind that GCC is almost certainly masked for good reason. It's not like you're using a binary distro and only need a compiler for a few packages. Feel free to try it in the knowledge that if it breaks your system, you get to keep the pieces. -- Neil Bothwick Sects, sects, sects, is that all you monks think about? signature.asc Description: PGP signature
Re: [gentoo-user] which -march flag to pick for Intel Core 2 Duo in make.conf?
Neil Bothwick [EMAIL PROTECTED] writes: When the devs consider it suitable for at least the testing branch or when you do echo =sys-devel/gcc-4.2* /etc/portage/package.mask, whichever comes sooner. Even that will not work (yet) as gcc-4.2 is not actually masked it is not keyworded. -- [EMAIL PROTECTED] mailing list
Re: [gentoo-user] which -march flag to pick for Intel Core 2 Duo in make.conf?
On 5/24/07, Neil Bothwick [EMAIL PROTECTED] wrote: Bear in mind that GCC is almost certainly masked for good reason. It's not like you're using a binary distro and only need a compiler for a few packages. Feel free to try it in the knowledge that if it breaks your system, you get to keep the pieces. Ain't it the truth! No, I wasn't asking with the anxiety to hurry things up - I was asking more about an estimated release time, whether it will be a month, 2 months, 3 months, etc. I'm not really looking to experiment with the cutting-edge releases right now. My aim is to build a fast, stable system for my computations, which ultimately brought me to another major decision: 32-bit or 64-bit... I run simulations which I write in C and numerical computations which I run in Mathematica (which has just released the 64-bit version). Would a 64-bit system significantly benefit these applications? -- [EMAIL PROTECTED] mailing list
