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 RepliesAs i undertsand - out of 1GB of the virtual Address space for Kernel from 3GB to 4GB of the process address space, Kernel image (code, data, bss, stack, heap) resides staring @0x0 address. Vmalloc area starts either at the end of Physical ram size or at 896M. This 896M cap is mandated to ensure that minimum of 128MB is reserved as vmalloc_reserve for vmalloc,kmap etc.
Is the understanding correct? Now trying to map Physical Zones into this 1GB address space
Initial 16MB is mapped to ZONE_DMA
16MB - 896MB is mapped to ZONE_NORMAL
896MB - 1024MB is mapped to ZONE_HIGHMEM
Does this mean that Kernel image is residing in ZONE_DMA area? Any call to vmalloc() in kernel code will return address beyond 896M? insmod of any LKM will internally invoke vmalloc() to obtain contiguous area - where will this code physically located along with rest of kernel code in ZONE_DMA or in ZONE_HIGHMEM?
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 use top to see memory usage, I have 65gb ram but only 1.3gb of it free and remaining is shown as used. When I ran my program It gives memory insufficiency error. Although no other program is using the remaining 63.7gb ram it is hold. How can I get free the unused ram?
View 3 Replies View RelatedHow can I get the physical address corresponding to a virtual address in linux by using /proc file system
View 1 Replies View RelatedA process is trying one access to memory, for example through an array (ex.: vect[0]=123. What happens?
Here below what I guess but I'm not sure and accept any comment (please, distinguish between "the system" and "the CPU" in case).
Let's suppose swapping to disk disbled.
We have two scenarios: without and with cache.
If no cache is present in the system:
1. The CPU must discover the phys addr of vect[0] virtual addr. To do that, has to read from 3 (or 2 depending on the system?) pages tables, stored in memory as well.
2. The CPU writes to the final address.
These mean 4 memory accesses.
If cache is present:
1. Like above but, if the pages tables are in cache, we have 3 accesses to that.
2. If the req. page is not in cache, it's reads from ram and transferred to it. Afterwards, cache is written.
In the best case we have 4 cache accesses.
clarify me with ulimit output and memory limit?
ulimit -a output:
core file size (blocks, -c) unlimited
data seg size (kbytes, -d) 1572864
[code]...
if i attach a shared memory to my process whch part of the address space it will add(like stack, heap, data, code...).
View 3 Replies View RelatedI have a very weird memory issue (as you may have guessed from the title). There's a discrepency between the memory accumulated by the various applications (using "ps -eF" to collect that) and the memory reported by system monitor/"free" Basically, I have around 0.5GB of memory that is not occupied by any application, but is not free as well. (It is not used as cache as well)
[Code].....
Why linux uses swap space, even if there are free physical memory available.
View 4 Replies View RelatedI am looking for free database that has low memory usage and innodb and memory like engins that has C API and support trigger and client/server support for using in embedded linux systems.
View 8 Replies View Relatedi had configured the opennms but i didint able to get the disk space and memory alert by mail... and also i need a plgin gor opennms can u tell me wat plugins suit for opennmms monitoring tool ...
View 2 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?
we found that if we use 'top' to show the memory usage of a server (SuSe Linux 10), we can get virtual memory usage as well as 'Resident memory' usage. For virtual mem or a particular process, it is around 1.1GB, which is large but for resident memory, it only consumes 300MB. Are there anyone who knows what the differences are? I would also like to know whether the difference (1.1GB - 300MB) = 800MB are actually available for use by other applications in the system.
View 1 Replies View RelatedI am writing an application that wants to access periphals registers outside the standard (allowed) memory area.
Doing so gets me "segmentation fault".
I know, this is natural behaviour.
One way of getting around this is writing the module which has to be loaded by linux. I will consider this some time later.
For now, I want to come to some quick result and allow linux or gcc compiler to write to those memory areas of periphals. Is there a direct way to do so?
I'm running an embedded Linux kernel, and I want to obtain a real memory address from user space. After goggeling a little, I found that the only way was to use mmap to access /dev/mem. But I never used mmap. I want to load a program in memory, in order to make it available from another processor, that has access to the DDR, but not to the flash memory where program is stored. Here is the code I use:
Code: // Open file and get its size
FILE* program = fopen(argv[3],"rb");
fseek(program, 0, SEEK_END);
long program_size = ftell(program);
fseek(program, 0, SEEK_SET);
// Prepare memory to copy it in
void* program_address = malloc(program_size+1);
FILE* memory_stream = fmemopen(program_real_address, program_size + 1, "wb");
[Code]....
Logical Memory Space of 4GB is divided in to 3GB User Space and 1GB Kernel Space. Always. Correct?
1. How can we change it? (just changing value of PAGE_OFFSET is okay?)
2. If system have only 256MB of memory (embedded system) and suppose Kernel Modules eat away all the memory during boot. User space will be left will no memory. Is this case possible?
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 need to write script to look for the presence of memory allocation calls without corresponding calls to free the memory
View 5 Replies View RelatedI would not exactly consider myself a newbie but this is a bit of a newbie question so here it goes.
When I run top I see used memory and free memory. When I first boot the system there is lots of free memory in about a day or two that memory whittles down from 2GB of Free mem(of 4GB) to 20MB and then maintains 20-50MB of free memory. This seems to be consistent across different servers. At first I thought there had to be some major memory leaks but it just seemed to prevalent to not have been noticed before.
I found a better way to gauge memory usage is the use of the free command. Now I am confused though, what is Free memory as it is defined and monitored in top?
When 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 have a query regarding top & virtual memory. When we run top it show VIRT (Virtual Mem), RES (Resident Mem) & SHR (Shared Memory). The total virtual memory of my machine is 4 GBs (2 GB RAM + 2 GB Swap), but still I am able to see a process showing 4000m virtual memory column. what it means, as its show VIRT Mem more than actual available VIRT memory
View 1 Replies View RelatedWas wondering if anyone can explain briefly the relationship of "cache" and free memory in the "free" memory command.
View 2 Replies View RelatedI'm trying to meter my memory usage. When I use these different programs, they all show me using different amounts of RAM.
View 2 Replies View Relatedim trying to collect some data. Is there a way to get the free memory stats over the past few days from some file... i looked into the sar log files but they dont have date stamps in them!
View 6 Replies View RelatedI have a computer with 16GB of ram. At the moment, top shows all the RAM is taken, (NOT by cache), but the RAM used by the various processes is very far from 16GB.I have seen this problem several times, but I don't understand what is happening.My only remedy so far has been to reboot the machine.
View 1 Replies View RelatedI've come across a really strange issue with one of my RHEL servers. The "free" command shows that 7019 MB of memory are actually in use by my system, but when summing up the actual usage (or even virtual usage like the example below) it doesn't add up - the sum is far less than what is reported by "free":
Code:
[root@server1 ~]# free -m
total used free shared buffers cached
Mem: 12011 7946 4065 0 4 23
-/+ buffers/cache: 7919 4092
[code]....