I am reading the field rss in the mm_struct but to pass on all the processes I use the macro for_each_task (defined in sched.h) - what happens that when I boot I get the folloing kernel panic ".. To kill the idle task.." how I can check if it's the idle task I then do break in my loop (for_each_task). Thanks.
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Oleg Goldshmidt Sent: Tuesday, December 16, 2003 6:48 PM To: moses Cc: [EMAIL PROTECTED] Subject: Re: Rss in ps/top "moses" <[EMAIL PROTECTED]> writes: > Hi all > > The man page doesn't *really* say what it's .Does anyone know what is > the exact meaning of this field - it's hard to belive that rss is the > the number if current memory resident in 1024 bytes. I run several > examples that show it the man page for rss > > -- > rss the real memory (resident set) size of the process (in > 1024 byte > units). OK, here is *really* what it is ;-) RSS (resident set size) is the amount of memory mapped in RAM, per process. There may be unmapped pages, but that is often the first stage of swapping the page away or discarding it altogether, so this is not as bad as it sounds. Neither SIZE nor RSS fields count the page tables or the task_struct of the process: those occupy at least 12K of memory that is always resident. SIZE is the virtual size of the process (code+data+stack). If you are really interested, go to your resident (pun intended) kernel source tree. The header include/linux/sched.h defines task_struct and mm_struct that contain the relevant per-process info. Look at struct task-struct, it contains struct mm_struct *mm; and that, in turn, contains unsigned long rss, total_vm, locked_vm; Now look at the /proc interface to the per-process memory usage: /proc/<pid>/status. Here is my bash: $ ps PID TTY TIME CMD 2678 pts/3 00:00:00 bash 2689 pts/3 00:00:00 ps $ egrep "^Vm" /proc/2678/status VmSize: 2580 kB VmLck: 0 kB VmRSS: 1400 kB VmData: 276 kB VmStk: 24 kB VmExe: 508 kB VmLib: 1444 kB This is more detailed than ps or top. VmData is the heap. VmStk is the stack. VmExe is the statically linked stuff. VmLib is shared libraries. All this comes from a function called task_mem() from fs/proc/array.c. Vm{Size,Lck,RSS} come directly from task_struct->mm as explained above. Vm{Data,Stk,Exe,Lib} are obtained by traversing the process vmas that have all the details as flags. Hope it helps, -- Oleg Goldshmidt | [EMAIL PROTECTED] ================================================================To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
