Rollercoaster
-The BlacKCoaT Operative-
yes it will work fine.. dont depend on the seemingly hightech talk goin on
i assure u no one actually knows anything
i assure u no one actually knows anything
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eddie
El mooooo
Mediator the explanation given by you is theoretical but practically Linux kernel has a problem which was first identified in 2001. 32bit Linux Kernel splits the 4GB memory in two parts of 1GB and 3GB. Now kernel needs to map virtual space for every process to physically available memory but at any given point *unpatched* Linux kernel can map only 1GB of kernel virtual space to the physical memory. Further, out of this 1GB Memory, 128MB is reserved for storing memory mapping and paging table structures which is done only when kernel has to handle huge amounts of physical memory (>=1GB). This in turn means that Linux kernel can *effectively* access only 1GB - 128MB = 896MB of physical memory at any given time.mediator said:
To solve this problem, two things were put under development. One of them was community driven 2GB/2GB and 3GB/1GB mem split patches. This was done to increase the amount of memory accessible by kernel space to 2GB and 3GB respectively. This approach was not widely accepted because it was more of a hack put together by a few developers so another set of patches was developed by kernel devs. This is known as HIGHMEM support and comes in two forms i.e. 4GB and 64GB memory support. 64GB HIGHMEM support was developed for processors like PentiumPro that were released with special instructions to address 4GB Memory limitation and increased it to 64GB.
This HIGHMEM support sounds interesting but it has its own share of problems. It is still not well tested and breaks drivers on random. Also, I/O devices cannot access HIGHMEM support directly and rather need to go through specific processes in kernel space. This leads to unnecessary overhead in kernel space and if possible, it should be avoided. Thus, moving on to 64bit kernel is advised.
Now coming to the thumb rule.
1) Anything below 896MB of Physical memory can be accessed directly by 32bit kernel. Also 64bit binaries are larger in size and they will take more space in RAM thus hogging your memory. This will nullify the performance boost your are supposed to get because you simply don't have enough RAM hence 32bit kernel and 32bit applications are recommended.
2) Next, we move to the limit of 896MB - 1GB. Here you need to make a choice. If you are very picky and do not want to waste even the 128MB of RAM then 64bit kernel and 32bit applications are recommended. The idea is NOT to enable HIGHMEM support just to access that 128MB of RAM because it increases kernel overload without much benefit but use the full amount of RAM at your disposal. 32bit applications are recommended for the same reason that is given above.
3) After this we come to >1GB Physical memory. Now here you have a choice of using HIGHMEM support (or) using just 64bit kernel (or) moving completely to 64bit system. Here, it totally depends on you and your choice but going to a full 64bit system is recommended because:
a) It avoids using HIGHMEM which is still not well tested.
b) 64bit kernel will address memory limitations and provide you a little extra performance boost.
b) 64bit binaries are known to be larger then 32bit binaries in Linux environment but the extra physical memory at your disposal allows you to gain that little extra by optimizing them for 64bit and not care about memory hogging.
Hence the thumb rule...
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mediator
Technomancer
Hmmm......I didn't know something like that existed practically! Neways I'll be pleased if u enlighten me on following questions.
1. If the bug was founded in 2001, then whats the present status?
2.
Neways I hope the thumb rule will be eliminated in future 32 bit Linuxes and I wonder if they are having trouble with 32 bit, then how'll they manage 64 bit and how'll they partition the exabytes!!
1. If the bug was founded in 2001, then whats the present status?
2.
Is it 64 bit HIGHMEM that u mistakenly typed as 64 GB?? IF not so, then how 4GB was increased to 64 GB? I didnt get this one!eddie said:
Neways I hope the thumb rule will be eliminated in future 32 bit Linuxes and I wonder if they are having trouble with 32 bit, then how'll they manage 64 bit and how'll they partition the exabytes!!
eddie
El mooooo
It is not a bug but a limitation that has been addressed using patches. The current status is that both HIGHMEM 4GB and 64GB patches are present in official kernel. You can enable it if you have more than 1GB RAM but with earlier said kernel overload.mediator said:
The answer lies in PentiumPro architecture and the PEA extension that it came with. These processors supported 36bit which translated into 64GB of physical memory support. Thus the kernel was made to support full memory range which could be supported by the processor but as the user land is 32bit, each process can't grow beyond 4GB. If you remember...this is why 36bit experiment of Intel failed miserably
When we will near exabytes, I am sure we will know about the limitations and they will be dealt with accordingly
Eddie can you provide some links on this stuff, if you have some handy. I do understand part of it cos I have come across it while compiling a kernel. But still a major part of the explaination is unclear to me. If you can direct me to some resources that explain this, that would be great.
Well as per what's the discussion's going on you'd be better off using a 32-bit Linux. I can't explain you why, so well cos I personally don't have it clear in my mind.savithk said:
But you'd save yourself a whole load of trouble if you go for a 32 bit linux for now. No real need to upgrade the RAM or anything.
Yes 64 bit linux distros are available in CD's. Well to be frank, a distro that comes in a CD is too minimalistic. If you can get some DVD that would be real great. Or multiple cd's.
A single cd of ubuntu linux for 64-bit platform can be delivered to your house free of cost in about a month's time from shipit.ubuntu.com
Hmm all right will search for it in free time. Maybe subscribe to gentoo-user mailing list too after the exams.eddie said:
If I get it right, highmem can break a few things. Is it?mediator said:
BTW, Highmem is a patch? Cos I have seen 'highmem' option while compiling the kernel, in it's description it says something like, to be used only if RAM is > 1GB.
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JGuru
Wise Old Owl
@Savithk, It' better that you go for 32-bit version of Linux. Try installing Suse 10.1 DVD (32-bit).
DVD is always better, no one wants to change CDs in between installation.
So go ahead with Suse 10.1 Linux installation. I'm sure you'll like it very much.
As far as the partitioning the disk is concerned, have atleast 10 GB of unpartitioned
space, during partitioning choose the option "Allocate from the free space available"
Suse Linux will automatically allocate the partitions for you. Or if you want to
manually partition the hard disk, allocate 9 GB for root ('/') & 1.5 GB for swap.
DVD is always better, no one wants to change CDs in between installation.
So go ahead with Suse 10.1 Linux installation. I'm sure you'll like it very much.
As far as the partitioning the disk is concerned, have atleast 10 GB of unpartitioned
space, during partitioning choose the option "Allocate from the free space available"
Suse Linux will automatically allocate the partitions for you. Or if you want to
manually partition the hard disk, allocate 9 GB for root ('/') & 1.5 GB for swap.
eddie
El mooooo
Yeah you got it more or lessmediator said:
In simple words, if you have anything above 1GB RAM you need 4GB HIGHMEM option enabled...anything above 4GB RAM needs 64GB HIGHMEM option enabled.
__________
It was developed as individual patch and then imported in official Kernel as an option.tech_your_future said:
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gary4gar
GaurishSharma.com
u need to create root(/) a ext3 partion of atleast 10gb & a swap partion of twice sixe of ur ram something like pagefile in windows.
u can use any tools like gparted or partion magic or inbuilt installer can also do this.
linux installion is little bit same as u would install windows. so if u know windows u can install linux also.
u can use any tools like gparted or partion magic or inbuilt installer can also do this.
linux installion is little bit same as u would install windows. so if u know windows u can install linux also.
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