If i create virtual environment by anaconda,
Are there any restrictions on this environment?
For example.
My computer has 8 core CPU and 32GB memory.
and I create 2 virtual environment (names : ENV1,ENV2)
ENV1 only can uses 4 core CPU and 10GB memory.
ENV2 only can uses 4 core CPU and 10GB memory.
Is it right?
Related
Machine specification : 5 GB RAM and 2 TB HDD. On this machine, I have installed Oracle virtual box and now I have to generate a virtual machine of 16 GB RAM and 500 GB HDD. But these both should be generated using HDD space. Can anyone guide me on how I can use HDD space as RAM in virtual machine. This is regarding Windows.
On my Mac, I have 8 cores working when I run htop.
I can modifyvm to have 8 cores in my virtual machine as well, but is it a one to one mapping?
Thus, if I set 4 virtual cores, do I have the power of 4 physical cores or do I have the power of 8 distributed on 4? Hence, does it make sense to have multiple cores in a vm regarding the overall performance or does it only make sense if you have processes that do not work well without parallelisation?
Given a 32-bit/64-bit processor can a 4GB process run on 2GB RAM. Will it use virtual memory or it wont run at all?
This is HIGHLY platform dependent. On many 32bit OS's, no single process can ever use more than 2GB of memory, regardless of the physical memory installed or virtual memory allocated.
For example, my work computers use 32bit Linux with PAE (Physical Address Extensions) to allow it to have 16GB of RAM installed. The 2GB per process limit still applies however. Having the extra RAM simply allows me to have more individual processes running. 32bit Windows is the same way.
64bit OS's are more of a mixed bag. 64bit Linux will allow individual processes to map memory well in excess of 32GB (but again, varies from Kernel to Kernel). You will be limited only by the amount of Swap (Linux virtual memory) you have. 64bit Windows is a complete crap shoot. Certain versions will only allow 2GB per process, but most will allow >32GB limited only by the amount of Page File the user has allocated.
Microsoft provides a useful table breaking down the various memory limits on various OS versions/editions. Unfortunately there is no such table that I can find with cursory searching for Linux since it is so fragmented.
Short answer: Depends on the system.
Most 32-bit systems have a limitation of 2GB per process. If your system allows >2GB per process, then we can move on to the next part of your question.
Most modern systems use Virtual Memory. Yet, there are some constrained (and various old) systems that would just run out of space and make you cry. I believe uClinux supports both MMU and MMU-less architectures. Most 32-bit processors have a MMU (a few don't, see ARM Cortex-M0) and a handful of 16-bit or 8-bit have it as well (see Atmel ATtiny13A-MMU and Atari MMU).
Any process that needs more memory than is physically available will require a form of Memory Swap (e.g., a partition or file).
Virtual Memory is divided in pages. At some point, a page reside either in RAM or in Swap. Any attempt to access a memory page that's not loaded in RAM will trigger an interruption called Page Fault, which is handled by the kernel.
A 64-bit process needing 4GB on a 64-bit OS can generally run in 2GB of physical RAM, by using virtual memory, assuming disk swap space is available, but performance will be severely impacted if all of that memory is frequently accessed.
A 32-bit process can't address exactly 4GB of memory in practice (some address space overhead is required by the operating system), so it won't run. Depending on the OS, it can probably run a process that needs > 2GB and < 3-4GB.
My original question is that, is this technically rational to check the required heap-size of my Java program on Windows 7, via VisualVM, and come to this conclusion that the program will require the same amount of heap on Linux(RedHat) as well?
I don't know how the system(OS or even CPU and RAM), affect memory management of JVM.
well, the windows is my development system with 4GB of RAM and a Core 2 Due CPU, however the
Linux is the production system with 32GB of RAM and multiple powerfull processors,
Actually, my concern is that the program on Linux might need more memory. less is ok.
I have one physical machine which has 4 CPUs. I want to have some VM on it. The goal of my work is finding CPU utilization. But I am confused how the CPU usage of VMs and physical machine are related. Is there a relation between CPU utilization of VMs and physical machine? How should I measure the CPU utilization of each VM? What is the CPU utilization of the physical machine?
If you are using any xen enabled hypervisor, you can use xenmon or xentop in your Dom0(physical machine) to check the utilization or performance of your VMs.
You can do so by typing xentop(it is /usr/sbin/xentop in my case) on the command line which will give you all the info you are looking for. Alternatively you can use xenmon -l command (/usr/sbin/xenmon.py python script) in my case which shows all the live information about your VMs.