Query on RAM Memory

Operating Systems Linux Red Hat Query on RAM Memory

09-30-2011

Registered User

108, 4

Join Date: Jul 2011

Last Activity: 7 June 2017, 8:42 AM EDT

Location: leeds, UK

Posts: 108

Thanks Given: 12

Thanked 4 Times in 4 Posts

Code:

 
use top | more

and look in %MEM

robo

View Public Profile for robo

Find all posts by robo

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Filesystems, Disks and Memory

Maximum Memory RAM for windows 7 32 bit

Hi, i have just installed 4 gb RAM ddr3 on OS Windows 7 32 bit. In "manage peripherals" i see this section: Memory installed (ram) : 4,00 gb (2,30gb usable) Why only 2,30 gb usable ? In Windows 7 32bit the maximum size is not 3,00gb ? see file attached, please

2. Programming

Memory Allocation Query

When we dynamically allocate the memory say 100 integers say int *x = new int(1000); then does entire chunk of memory gets allocated at once after the completion of the statement? I mean will the the concept of page fault come into picture over here?

3. Ubuntu

Find defective ram memory

How do I find if I have defective ram in my computer. I don't have a cd-rom, so I can't use a bootable cd.

4. Solaris

Ram memory fails.

Hi All, Ram memory always fails,i did not find the reason...........any one can help i this.:wall:

5. Shell Programming and Scripting

Retrieve RAM memory size from "top" command output

Hi, I am trying to get the system RAM size from "top" command's output by the following but it is not working. top | sed "s/^Mem.**\(*\), *//"

6. Solaris

RAM memory display

Hi How to display RAM memory info under Sol10 ? I need info like : - how many slots is available in MoBo - how RAM is plugged into those slots - total number of RAM memory size and size divided in each slot ths for help.

7. Filesystems, Disks and Memory

RAM memory checker / bad lister

A bit of background I'm running a Nexenta (OpenSolaris kernel + a number of Debian tools) server running a ZRAID of 3x 1TB SATA2 drives (essentially a RAID5 formatted in ZFS, for those who aren't familiar with zpools). When running the ZFS scrub command (ZFS's equivelent of fsck) I get a number...

8. UNIX for Dummies Questions & Answers

How to accurately determine memory (RAM) information

I'm writing a shell script to display as much useful information on physical and virtual memory availability and usage as possible. I need a CLI tool to print these numbers for me. The utilities that I know to give out some statistics are the following: free top vmstat sysctl In Linux...

9. Solaris

RAM Physical Memory usage by each Process.

Hi All, I am trying to find the physical memory usage by each process/users. Can you please let me know how to get the memory usage?. Thanks, bsraj.

10. UNIX for Dummies Questions & Answers

Amount of RAM (Memory)

How do i check/get the total amount of RAM, on a machine running UNIX?

LEARN ABOUT REDHAT

mlockall

MLOCKALL(2)						     Linux Programmer's Manual						       MLOCKALL(2)

NAME

       mlockall - disable paging for calling process

SYNOPSIS

       #include <sys/mman.h>

       int mlockall(int flags);

DESCRIPTION

       mlockall  disables paging for all pages mapped into the address space of the calling process. This includes the pages of the code, data and
       stack segment, as well as shared libraries, user space kernel data, shared memory and memory mapped files. All mapped pages are	guaranteed
       to  be  resident  in  RAM  when	the  mlockall  system call returns successfully and they are guaranteed to stay in RAM until the pages are
       unlocked again by munlock or munlockall or until the process terminates or starts another  program  with  exec.	 Child	processes  do  not
       inherit page locks across a fork.

       Memory  locking has two main applications: real-time algorithms and high-security data processing. Real-time applications require determin-
       istic timing, and, like scheduling, paging is one major cause of unexpected program execution delays. Real-time applications  will  usually
       also  switch to a real-time scheduler with sched_setscheduler.  Cryptographic security software often handles critical bytes like passwords
       or secret keys as data structures. As a result of paging, these secrets could be transfered onto a persistent swap store medium, where they
       might  be accessible to the enemy long after the security software has erased the secrets in RAM and terminated. For security applications,
       only small parts of memory have to be locked, for which mlock is available.

       The flags parameter can be constructed from the bitwise OR of the following constants:

       MCL_CURRENT Lock all pages which are currently mapped into the address space of the process.

       MCL_FUTURE  Lock all pages which will become mapped into the address space of the process in the future. These could be	for  instance  new
		   pages required by a growing heap and stack as well as new memory mapped files or shared memory regions.

       If MCL_FUTURE has been specified and the number of locked pages exceeds the upper limit of allowed locked pages, then the system call which
       caused the new mapping will fail with ENOMEM.  If these new pages have been mapped by the the growing stack,  then  the	kernel	will  deny
       stack expansion and send a SIGSEGV.

       Real-time processes should reserve enough locked stack pages before entering the time-critical section, so that no page fault can be caused
       by function calls. This can be achieved by calling a function which has a sufficiently large automatic variable and  which  writes  to  the
       memory  occupied  by  this  large array in order to touch these stack pages. This way, enough pages will be mapped for the stack and can be
       locked into RAM. The dummy writes ensure that not even copy-on-write page faults can occur in the critical section.

       Memory locks do not stack, i.e., pages which have been locked several times by calls to mlockall or mlock will be unlocked by a single call
       to  munlockall.	 Pages	which  are  mapped to several locations or by several processes stay locked into RAM as long as they are locked at
       least at one location or by at least one process.

       On POSIX systems on which mlockall and munlockall are available, _POSIX_MEMLOCK is defined in <unistd.h>.

RETURN VALUE

       On success, mlockall returns zero.  On error, -1 is returned, errno is set appropriately.

ERRORS

       ENOMEM The process tried to exceed the maximum number of allowed locked pages.

       EPERM  The calling process does not have appropriate privileges. Only root processes are allowed to lock pages.

       EINVAL Unknown flags were specified.

CONFORMING TO

       POSIX.1b, SVr4.	 SVr4 documents an additional EAGAIN error code.

SEE ALSO

       munlockall(2), mlock(2), munlock(2)

Linux 1.3.43							    1995-11-26							       MLOCKALL(2)

Red Hat