If you’re here: https://github.com/torvalds/linux/blob/master/fs/ext4/file.c#L360 You have access to these two structs inside the ext4_file_mmap function: I am changing the implementation of this function for dax mode so that the page tables get entirely filled out for the file the moment you call mmap (to see how much better performance not taking any pagefaults gives us). I have managed to get
Tag: memory-management
where is file descriptor stored in process memory?
When a function A is called from a point of execution, internally it is a JMP statement to the address pointing to function A. So the current point of execution is saved onto the stack, the PC loads the address of the called function A and continues. To get back to the point of execution after the function call, the
Increasing memory through terminal in linux through “-XX:PermSize=192m -XX:MaxPermSize=2g -Xms2g -Xmx2g”
I am running java developer IDE and in a process of trouble shooting a module . For this i have increased the logging memory of the tool, Now when logging it error is coming on console as i am using below command for increasing memory earlier it is my system memory is 16 GB through the command cat /proc/meminfo but
infinite loop malloc in a 32 bit kernel with 4 Gb RAM and 10 Gb Swap Partition
Let’s say I have a 32-bit kernel. 4 Gb RAM, 10 Gb Swap Partition. I have a process which has malloc in an infinite loop. So, eventually system’s OOM would kill the process. Here are two arguments. Argument 1: Since, it’s 32 bit Kernel with a Virtual address split of 3:1 i.e. 3Gb for user space and 1 Gb for
Which segments are affected by a copy-on-write?
My understanding of copy-on-write is that “Everyone has a single, shared copy of the same data until it’s written, and then a copy is made”. Is a shared copy of the same data comprised of a heap and bss segment or only heap? Which memory segments will be shared, and is this dependent on the OS? Answer The OS can
mmap: Cannot allocate memory
I have a C program that computes the page fault service time in C. For this program I have 2 large files (of less than 3GB each – almost the size of the RAM) I get the following compiler warnings: When I run it with the command I get the error What does the code do? We map both the
Does Linux have a page file? [closed]
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Where is the src code point where Linux kernel establish mapping virtual-physical address?
As I know, when program try to access virtual address that the corresponding PTE is NO present , kernel will trigger page fault and page fault handler will handle it. In handler, if fault is caused by no physical mapping to the PTE, kernel should allocate free physical page and write physical address to PTE. I found many functions like
Why malloc is faster than static memory allocation in my test program?
I have a test program. I get this result when executing it in ubuntu trusty 64 bit. malloc time:9571 static time:45587 Why malloc is faster than static memory allocation,or my test program is wrong? The test program is like this. Answer That benchmark is essentially meaningless because most of what it is measuring has little relationship with the use of
check if a memory page is loaded into memory
Given a virtual address, I want to know if the memory page mapped into this virtual address has been loaded into memory or in disck. Is there anyway to do check that in user level program? I am using CentOS 7. Answer You can use the mincore system call for this. mincore – determine whether pages are resident in memory