Questions tagged [memory-management]
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52 questions
1 vote
0 answers
113 views
Too slow Tiered Memory Demotion and CPU Lock-up(maybe) with cgroup v2 memory.high
We are currently testing tiered memory demotion on a machine equipped with a CXL device. To facilitate this, we created a specific script (https://github.com/hyun-sa/comem) and are using the memory....
- 11
2 votes
1 answer
79 views
Are the page tables of the process preempted swapped out if there is a dearth of memory for new process
Suppose process A has been preempted to allow process B to run. If system memory is low and the kernel needs to reclaim memory for process B, is it possible for the page tables of process A to be ...
10 votes
3 answers
1k views
Why can ZONE_NORMAL only go up to 896MiB on 32-bit x86 processors?
According to Linux Kernel Development by Robert Love, p. 233: Because of hardware limitations, the kernel cannot treat all pages as identical. Some pages, because of their physical address in memory, ...
- 103
0 votes
0 answers
60 views
Intel VM-exit EPT_VIOLATION error_code
I'm using trace-cmd on a Linux host running a qemu/kvm VM in order to check VM-exit events related to EPT_VIOLATION reason. root@eve-ng62:~# trace-cmd record -b 20000 -e kvm:kvm_page_fault -e kvm_exit ...
- 385
0 votes
0 answers
229 views
Allocating contiguous physical memory using huge pages in kernel module
0 I need a kernel module that allocates 8MB of physically contiguous memory using 2MB huge pages, in response to a user-space mmap() request. While I’ve successfully used alloc_pages() with 4KB pages ...
1 vote
1 answer
299 views
Understanding memory limits in a systemd service: Are they per-process or combined?
I have a systemd service named vcoagent.service running on my Linux system, and I'm trying to understand how memory limits specified for the service (Memory: 300.3M (limit: 500.0M)) apply to the ...
4 votes
1 answer
1k views
Process memory layout - difference between heap, data and mmap areas
I see in the web many conflicting or unclear descriptions of the memory layout of a Linux process. Usually the common diagram looks like: And a common description would say that: The data segment ...
- 6,965
5 votes
1 answer
6k views
Is there a way to set a hard cap/limit on how much RAM Chrome can use?
I'm using Linux on my Steam Deck (SteamOS/Arch Linux). Is there a method to set a hard cap/limit on the maximum total RAM Chrome can use with command line arguments? (to 8 GB out of the device's max ...
- 51
0 votes
1 answer
122 views
Memory total shown on Linux on 8GB memory PC is only 7038920 kB
Why linux /proc/meminfo show:" 1 MemTotal: 7038920 kB " (proc most likely is to mean Kibibyte) in a PC of 8 GB memory RAM, although its Kibibyte is 7812500 ?
user575072
0 votes
1 answer
118 views
Do page tables used to store kernel stack pointer when context switch happen in kernel mode of the process?
I have two questions; Suppose a user space application/process is running in kernel mode. I understand if a context switch is happened now, the kernel stack pointer of that process is stored in the ...
- 309
5 votes
1 answer
3k views
How does mmio get routed to io devices?
I am trying to understand how IO devices are mapped into the 'regular' memory address space on modern x86 machines running Linux. Some details which I am trying to make sense of are: cat /proc/iomem ...
- 210
1 vote
1 answer
413 views
On some UNIX implementations, it is not possible to call free() on a block of memory allocated via memalign()
I use Linux only but I want to understand what this means: From the Linux Programming Interface: Blocks of memory allocated using memalign() or posix_memalign() should be deallocated with free(). On ...
- 1,257
2 votes
1 answer
2k views
Can a Linux Swap Partition Be Too Big?
Can a Linux swap partition be too big? I'm pretty certain the answer is, "no" but I haven't found any resources on-point, so thought I'd ask. In contrast, the main Windows swap file, ...
- 399
0 votes
0 answers
287 views
How can i access the page table of a process from kernel using a custom syscall?
I am using Ubuntu 16.04, kernel: 4.17.4 I want to access the page table of a process. The idea is, inside a c code I will call a custom Syscall and the syscall will be able to access the page table of ...
- 1
0 votes
1 answer
242 views
Is vmalloc() allocate bytes of memory which is virtually contiguous maps to memory area from different physical pages?
vmalloc(size) allocates a memory of size long which is virtually contiguous but the physical mapping would not be contiguous. Does that mean the the virtually allocated size long memory actually lies ...
- 309