I need to write script to look for the presence of memory allocation calls without corresponding calls to free the memory
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I have been assigned a school project on detecting memory leaks in linux processes. I am reading.. but have found it hard and inefficient to go through the very vast documentation not knowing what to really look for. Could you please give me some guidelines on this subject?
View 4 Replies View RelatedHow do we allocate memory of struct? what i did was
Code:
int main()
struct amp
{
[code].....
cout <<"The size of 'struct' is"<< sizeof(struct amp)<<"and it is located at"<<struct amp*s = malloc(sizeof(struct amp))<<endl;
it gives me an error---
In funtion 'int main()':
error: expected primary-expression before 'struct'
error: expected ';' before 'struct'
I'm performing some explorations in terms of memory allocations in ANSI C, using the following compiler:
gcc version 4.1.2 20080704 (Red Hat 4.1.2-46)
and I started to try to make the compiler complain for a huge data structure, so I coded this:
[code]....
I mean, I can always read the man entry for gcc but I rather ask because I can then have interaction...
I want to allocate the continuous memory larger 128k for DMA process. But i can't used kmalloc() function for allocate the memory larger 128KB. allocate the continuous memory larger 128k for DMA process.
View 1 Replies View RelatedI'm trying to write a C program that extends an array to any user inputed size.
Code:
if (arraysize == 0) {
arraysize = (int) pos + 1;
a = (int *) calloc (arraysize,sizeof(int));
for (i = 0 ; i < arraysize ; i++ )
a[i] = -1;
code....
The program dumps with that sequence of inputs everytime, but might dump an input before or after if different positions are requested. Interestingly, when I tested pos = 2000..2008, I got no dumps. So is realloc somehow trying to extend the array into bad space?
I am using malloc and frees a lot in my program. It shows its allocated but when i remove it doesnt show as the memory is removed(I am using the top command to view VIRT memory usage). If this continously grows what would happen to my program (Will it go out of memory?)
View 4 Replies View RelatedHow do I write a script for my Linux that can show me total memory vs used memory and have it email me results if it's over 70 percent?
View 2 Replies View RelatedWhat is the real difference between system calls and normal function calls. Ultimately function calls too would be passed to kernel for some or the other work.
View 7 Replies View RelatedI've been looking into memory overcommitting in Linux using /proc/sys/vm/overcommit_memory, and I've read a few articles which don't say the same thing. This doc, under the heading "Going in the wrong direction", goes on to say, "values 1: do overcommit, and 0 (default): don't", but then in the next few lines, it mentions, amongst similar things, that this isn't actually true and that 0 means "guess about how much overcommitment is reasonable". That means that memory overcommit isn't disabled using value 0, right?
It also says that 1 indicates "never refuse any malloc()", with 2 meaning "be precise about the overcommit - never commit a virtual address space larger than swap space plus a fraction overcommit_ratio of the physical memory." The Red Hat magazine, on the other hand states, "if the value is 0, then the kernel checks to determine if there is enough memory free to grant a memory request to a malloc call from an application. If there is enough memory, then the request is granted. Otherwise, it is denied and an error code is returned to the application."
This sounds exactly like disabling overcommit. "If the value is set to 1, then the kernel grants allocations above the amount of physical RAM and swap in the system as defined by the overcommit_ratio value.... If the setting in this file is 2, the kernel allows all memory allocations, regardless of the current memory allocation state." In terms of values 1 and 2, that is the opposite of what the previous doc said, right? What is actually correct, and if it is possible to 'disable' overcommit?
How to write a value to a specific memory location in C language and how to access the same value ?
I am trying the same on fedora linux and i am trying to write the value to the 32-bit address.
I have encountered this problem of memory usage is increasing as the during the my program is being run until 1Mb is left then it stays at that.A part of the program is this:
Code:
#define WRITE_BUF_SIZE (1024*1024)
void post_data(const void *data, unsigned long size)
[code]....
I'm running Fedora 11 (2.6.30.10-105.2.4.fc11.i686.PAE) 8 GB memory on a AMD Phenom(tm) II X4 965 Processor, 4 core server I just built.The problem I have run into is any virtual machine that has >1024 MB memory assigned to it will not boot. As along as it has 1024 MB or less it boots fine.The symptom you see is a very quick message "Booting from hard disk" the screen then goes blank, you can't login through SSH, and can't ping the network address so I know it's not some crazy video problem hiding the boot process.The attachment are messages from a failed boot attempt.
View 4 Replies View RelatedWhen I play Bejewelled Blitz on Mozilla firefox or Google Chrome,, it is so painfully slow that it is frustrating, I have all the latest updates from Ubuntu installed including the Adobe flashplayer. Is there some way I can increase the graphics memory allocation?
View 5 Replies View RelatedI am trying to write a script to calculate the total amount of installed memory to use during an anaconda kickscript, so the swap file is created at 2 x the installed memory. I so far have the amount of installed RAM DIMMS but need a way to total them up and produce a varible I can use in the pre section of the install.
Code:
dmidecode -t 17 | grep Size | awk ' { print $2 }'
Output:
2048
2048
Note: on some servers there could be from 1 DIMM up to 16 DIMMS installed so the script needs to be able to handle this. I also can not use bc as it does not exist during the install stage. I am guessing I need a while loop to do this and use expr but do not know where to start for this logic.
I have a few multi-user servers in an academic laboratory. I am having a problem with some users maxing out the available RAM, causing such sever slowdowns the machine essentially crashes. My servers are Dell Power Edge's running Ubuntu 8.10 Server Edition (Not my choice). I would like to set a maximum limit on the amount of ram a user can utilize. This morning I experimented with setting limits via /etc/security/limits.conf and using ulimit. Neither of them prevented my test program, a simple infinite loop of mallocs, from crashing the server.
View 7 Replies View Relatedin gcc how to read a blank line ie a string of length 0.
my code: Code:
#include<stdio.h>
#include<string.h>
#include<string>
using namespace std;
[Code]....
Sed seems to react to the presence of "" in its input if the immediately following character makes the pair a recognizable code. In the code following see that the "a" and "" are missing in the output, and that the "c" caused sed to terminate at that point. Is there any way to prevent it reacting like this?
Code:
g y="the shell built-in command. The following character sequences
> have special meaning:
> a Alert (bell).
> Backspace.
>
> c Suppress trailing newline.
> f Form feed.
>
[Code]....
I want to check whether a USB is plugged in its slot from a C program. I want to make use of /proc interface for the same. During my reading i found that /proc/bus/usb/devices will tell how many USB devices are currently present.
So whether i can open this file and use stat call to identify whether the size is 0. If size is 0, i can assume no USB present. Else i can assume USB is present.
Whether my understanding correct. If USB inserted, how can i check the folders present in the USB stick.
I'm maintaining a c++ application running on a 64-bit RHEL5 server w/32GB ram, but compiled to be a 32-bit executable with g++. The application handles large amounts of data, and has lately been throwing a st9bad_alloc exception. "top" shows the application as dieing right around when VIRT=~3GB, SWAP=~1.5GB and RES=~1.5GB. In the core dump I can see that it's consistently failing to push_back() a piece of data onto a std::vector (which already has hundreds of thousands of objects in it).
I know 4GB is the maximum address space for 32-bit applications. I've learned from this lwn article that a 32-bit kernel reserves 1GB of address space, leaving 3GB for user space. However I'm not running a 32-bit kernel, so that really doesn't answer anything.I wrote a dummy app which called malloc() over and over in a for loop, and it is able to allocate right up to the 4GB before it fails. I don't understand why this one seems to be able to allocate more.
The only difference between the two apps (besides malloc vs std::vector:ush_back), is that the 3GB crashing application attaches to 512mb of shared memory.Anyone have any ideas why this application would be crashing at 3GB? Is there any more diagnostics I should be doing? I would ultimately like to port this to 64-bit for a number of reasons, but it is a big undertaking for my organization, and I'd like to better understand what's going on here.
A friend working in HPC environments commented me that he had an issue regarding the use of the malloc() function.What issue?He told me that he has had cases in where malloc() instead of returning a NULL pointer on failure, simply didn't change the original value of the pointer it was trying to use for allocation, thus forcing him to initialize pointers to be allocated with malloc() to NULL, so that he could be sure that if malloc() fails, a test for NULL would make sense.
View 12 Replies View RelatedThe algorithm for reading and writing disk blocks use the algorithm getblk to allocate buffers from the pool. In the algorithm getblk, if the kernel removes a buffer from the free list, it must raise the processor priority level to block out interrupts before checking the free list. Why ?Where can i find the C implementation of the above algorithm for buffer allocation in the linux source code ?
View 1 Replies View RelatedI am new to C and linux. My code below does arbitary writes but I cant figure out where or how it does it.
I am calling the insertNode() function with seq = 'MISSISSPPI$' and alphabets = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ$'
Code:
Weird behaviour I should mention is that when I check for NULL pointer in node->child[index], the unassigned values are not null anymore, they point to arbitary memory.
I need to include variables in a system() call. This is that I have:
[code]#include <iostream>
#include <stdio.h>
#include <stdlib.h>
using namespace std;
[Code]....
P.S.: I know this is a pointless redundant program, but it's part of a larger project learning process.
I have a problem in making multiple calls using PJSIP. I registered different accounts that implements IAccount and added that in the CallManager. When i try to make the calls from the same CallManager, I could able to make the first call. When second call is made the first call got cut and it is alerting and the same for the thrid call..Could anyone help me in this regard.
Note: Calls has to be made from different numbers to different destinations. Is it possible to make multiple outbound calls simultaneously from the same instance of CallManager?
Is that possible that SHM shared memory is counted as cache memory on Linux with kernel 2.6.18?If find it really odd since this memory is not file backed, but I have a piece of code that loads data using shm_open+mmap, and it generates an amount of cache memory in /proc/meminfo that corresponds exactly to the amount of shared memory (I load that data from a file but I am using posix_fadvise(fd,0,0,POSIX_FADV_DONTNEED) to ensure this file is not cached and I made sure that it is working as expected). As far as I know SHM memory was not tagged as cache memory with kernel 2.6.9.If it is the case it is really unfortunate since normally cache memory can be considered to be part of the "available" memory since it can be flushed promptly but this is clearly not the case with SHM memory... Is there an easy way to get the total amount of used SHM memory on a system?
View 4 Replies View RelatedWe recently ported an application over from IRIX to Linux, specifically SUSE Enterprise 11 and gcc (glibc 2.9). On IRIX there was a library trace utility call 'par' that allowed me to execute a C program and trace all the library calls it made, tracking how much time was spent in each call. I have been trying to find something similar for SUSE. I have found the ?trace programs (strace, ltrace, and ktrace) none of which is default installed on SUSE 11.Does any one have a suggestion on which ?trace to install and use or is there something else out there better?
View 1 Replies View RelatedI know there is a way to call winapi in runtime in windows. I want to ask how can I call a system call in gcc in runtime (when I don't know what it can be)? I don't mean syscall that I think is for calling only system calls and not library functions.
View 4 Replies View RelatedIs there a way to hook calls to new/malloc, delete/free in C++? I tried the following methods: LD_PRELOAD -> fails for malloc, because dlsym seems to depend on malloc -Wl,--wrap,malloc -> doesn't work for 'new' gcc hooks -> doesn't work always, e.g. for uclibc there are no hooks Are there any other methods I could try?
View 2 Replies View Relatedhow can I trace the method calls in Java during runtime?
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