Sponsored Content
Top Forums Programming Find Virtual address space size for process Post 302254862 by jim mcnamara on Wednesday 5th of November 2008 10:41:57 AM
Old 11-05-2008
Your assumption seems wrong to me.

First off, Shamrock showed you how to get address space there is for a process versus how much "physical" virtual space is available through hardware and disk files.

The "hardware" part is OS dependent. Your assumption is that somehow the system reserves virtual space for each process. NO. It does not. The system gives memory space via sbrk() or brk() calls to any process requesting it. brk() fails when there is no more virtual space to be had. sbrk() returns SBRK_FAILED and brk() returns -1 on failure.

If the system "set aside" memory ahead of time, then these calls would not be needed.
 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

How to find the size of Process Address space.

Hello, Please help me to know, How to find out the how much amount of process addres space is required/is used for/by a process. Tnx & Regards Vishwa. (1 Reply)
Discussion started by: S.Vishwanath
1 Replies

2. Programming

How to find out the stack size occupied for a process?

Hi, In Linux how to find out what will be the stack size allocated for a process? Actually i have to fork n number of processess, and will call exec. I will be execing an executable which is already multithreaded and each thread size is defined. My doubt is how to know if the size of the... (2 Replies)
Discussion started by: rvan
2 Replies

3. UNIX for Dummies Questions & Answers

how can i get The total size of the process in virtual memory om GB or MB

Hello all im using the ps -ef "args vsz" | some.exe but the result is in kb , is there some kind of way or flag ( didnt found in the ps man ) to convert me this data to GB or MG in human readable format ? Thanks (1 Reply)
Discussion started by: umen
1 Replies

4. Shell Programming and Scripting

find process size script

Hello i am working on a project here is part of script that i need a help in get process SpectroSERVER current size if it exceed 3850 MB then #pkill -TERM ArchMgr and wait to succfull shutdown message from the log file to proceed to the next step #tail -f $SPECROOT/SS/DDM/ARCHMGR.OUT... (7 Replies)
Discussion started by: mogabr
7 Replies

5. UNIX for Advanced & Expert Users

Can kernel process access user address space ?

Can kernel process access user address space ? (2 Replies)
Discussion started by: subhotech
2 Replies

6. Programming

How to get address space size that a process is allowed to use

Hi All, From C++, I just want to find the address space size that a process is allowed to use. For ex, in 32 bit OS the allowed address space is 4GB and in 64 bit OS I guess this is 16GB or more. I jsut want to find it in my C++ project. Is there any API calls that gives me such information.... (2 Replies)
Discussion started by: Sendil Kumar
2 Replies

7. UNIX for Advanced & Expert Users

Process self-exec and virtual memory size

Hello all, To do a self-exec or self-restart of a process when it crosses the threshold memory limit, I use the value of virtual memory size field from /proc/$pid/stat file and do a self-exec. According to man 5 proc vsize %lu Virtual memory size in bytes. I just want to... (2 Replies)
Discussion started by: matrixmadhan
2 Replies

8. UNIX for Dummies Questions & Answers

What would the physical address be for virtual address?

Hi guys, I got one problem which I definetily no idea. What would the physical address be for virtual address? 1) 2ABC 2) 3F4B Here is the page table:see attached Thank you sos sososososso much!! (0 Replies)
Discussion started by: lemon_06
0 Replies

9. Programming

PC RAM and process address space

Suppose I have 3 gb of ram and 250 gb hard disk in my pc. Now I wrote a simple C program having only one statement malloc() to allocate 4 gb of memory as 32 bit os can address 4gb address space then will the malloc succeed? If yes then how it will get extra 1 gb of memory? Does the process gets... (3 Replies)
Discussion started by: rupeshkp728
3 Replies

10. Programming

How to decrease virtual size of a process after cleaning all containers and using malloc_trim (0)?

Hello all i have simple server running on linux redhat 6.1 it is build with c++ in the server i have huge std vector that holds pointers to cache objects those cache objects holds allot of data from the DB any way ... in some point in time there is simple API that suppose to clean the... (2 Replies)
Discussion started by: umen
2 Replies
KSEG_TO_PHYS(9r)														  KSEG_TO_PHYS(9r)

NAME
KSEG_TO_PHYS - General: Converts a kernel-unmapped virtual address to a physical address SYNOPSIS
vm_offset_t KSEG_TO_PHYS( vm_offset_t addr ); ARGUMENTS
Specifies the buffer virtual address to convert to a physical address. DESCRIPTION
The KSEG_TO_PHYS routine converts a kernel-unmapped virtual address to a kernel physical address. Device drivers can use this physical address in DMA operations. Prior to calling KSEG_TO_PHYS, device driver writers often call one of the following routines to determine whether the address passed is a virtual address in the addressed kernel segment: IS_KSEG_VA Determines if the specified address is located in the kernel-unmapped address space. IS_SEG0_VA Determines if the specified address is located in the user-mapped address space. IS_SEG1_VA Determines if the specified address is located in the kernel-mapped address space. RETURN VALUES
Upon successful completion, KSEG_TO_PHYS returns the physical address. EXAMPLE
The following code fragment shows a call to KSEG_TO_PHYS: . . . caddr_t virt_addr; [1] unsigned phys_addr; [2] . . . if(IS_KSEG_VA(virt_addr)) { [3] phys_addr = KSEG_TO_PHYS(virt_addr); [4] . . . Declares a variable to store the user buffer's virtual address. Declares a variable to store the physical address returned by KSEG_TO_PHYS. Before calling KSEG_TO_PHYS, calls IS_KSEG_VA to determine if the virtual address is from the kernel-unmapped address space. If the virtual address is from the kernel-unmapped address space, then calls KSEG_TO_PHYS to convert the address to a corresponding physi- cal address. SEE ALSO
Routines: IS_KSEG_VA(9r), PHYS_TO_KSEG(9r) KSEG_TO_PHYS(9r)
All times are GMT -4. The time now is 10:02 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy