some friends are telling me that Workstation does allocate memory(RAM) from Windows startup even without starting VMWare Workstation is that true?
I have searched the net and I still have no answer.
It allocates virtual memory. Whether or not that memory is backed by physical RAM is up to the operating system.
Related
I got mongodb version 3.0 on linux redhat 6. The storage engine is MMAPv1.
I checked mongo memory usage on the server. I notice that virtual memory is 10 Gb which is far from mapped memory that is 4 Gb.
Is this situation correct or mongo server is running suboptimal?
It should be related to the glibc new virtual memory management since glibc2.10.
see here .
https://www.ibm.com/developerworks/community/blogs/kevgrig/entry/linux_glibc_2_10_rhel_6_malloc_may_show_excessive_virtual_memory_usage?lang=en
In a nutshell, the new malloc will allocate by default 8*cores*64MB on 64bit system for thread memory pool.
I'm currently using a combination of qemu-kvm, libvirtd, and virt-manager to host some virtual RHEL 6 machines. When I go ahead and attempt to bump the ram usage up above 4gb, the machines fail to start. What would even be the cause of this? Any information is helpful.
I'm running a 10 core, 3GHz Xeon processor, with 64 GB of ram.
I was looking for an answear but didn't find one.
I'm trying to create a new VM to develop a web application. What would be the optimal processor settings?
I have i7 (6th gen) with hyperthreading.
Host OS: Windows 10. Guest OS: CentOS.
Off topic: RAM that should I give to VM should be 50% of my memory? Would it be ok? (I have 16GB RAM)
Thanks!
This is referred to as 'right-sizing' a vm, and it is dependent on the application workload that will run inside it. Ideally, you want to provide the VM with the minimum amount of resources the app requires to run correctly. "Correctly" is subjective based upon your expectations.
Inside your VM (CentOS) you can run top to see how much memory and cpu % is being used. You can also install htop which you may find friendlier than top.
RAM
If you see a low % of RAM being used, you can probably reduce what you're giving the VM. If you are seeing any swap memory used (paging to disk), you may want to increase the RAM. Start with 2GB and see how the app behaves.
CPU
You'll may want to start with no more than 2vCPUs, checkout top to see how utilized the application is under load, and then make an assessment for more/less vCPUs.
The way a hosted hypervisor (VMware Workstation) handles guest CPU usage is through a CPU scheduler. When you give a vm x number of vCPUs, the VM will need to wait till that many cores are free on the CPU to do 'work'. The more vCPUs you give it, the more difficult (slower) it will be to schedule. It's more complicated than this, but I'm trying to keep it high level. CPU scheduling deep dive.
Hi I am trying to find the limit for xms and xmx on a 64 bit 2008R2 platform.
I have limited knowledge of this area.
Can anyone tell me if there are any issues with setting xmx and xms to 18gig. I have read about issues with garbage collection. The server has 24gig.
Thanks
Sid
I am running 65536M on 2008 R2 64-bit with no issues. Machine has 32GB physical (well, it's actually a VM, so it's virtual, but what isn't?). I actually came to your question to see if going to 96GB on a 32GB VM would be an issue, other than more disk thrashing.
as here mention, mongodb has limitation of datasize to 2GB in 32-bit machine with one single mongod instance. But I wonder 32-bit machine has 4GB addressable space in theory, and mongod can use this 4GB instead of 2GB for virtual memory usage. So why the answer is 2GB, not 4GB?
4Gb of addressable space is not the same as the memory space available for memory-mapped files opened by user applications. Some of the addressable space is reserved for the O/S kernel and memory-mapped devices such as video cards.
For example, 32-bit Windows limits user mode (and thus memory-mapped files) to ~2Gb RAM and total system RAM to ~3.5Gb.
For more reading, see:
Coding Horror: Dude, Where's My 4 Gigabytes of RAM?
MSDN: Managing Memory-Mapped Files
MSDN: Memory-Mapped Files
The majority of modern desktop and server environments starting moving to 64-bit almost a decade ago (see 64-bit operating system timeline on Wikipedia) so this isn't a limit that practically affects deployment.
You would only want to use 32-bit MongoDB in a development environment with limited data.
32-bit MongoDB processes are limited to about 2 gb of data. This has come as a surprise to a lot of people who are used to not having to worry about that. The reason for this is that the MongoDB storage engine uses memory-mapped files for performance.
By not supporting more than 2gb on 32-bit, we’ve been able to keep our code much simpler and cleaner. This greatly reduces the number of bugs, and reduces the time that we need to release a 1.0 product.
http://blog.mongodb.org/post/137788967/32-bit-limitations