Mems | Utils for viewing memory in Swift

by CoderMJLee Swift Version: Current License: MIT

X-Ray Key Features Code Snippets Community Discussions(10)Vulnerabilities Install Support

kandi X-RAY | Mems Summary

Mems is a Swift library typically used in Utilities applications. Mems has no bugs, it has no vulnerabilities, it has a Permissive License and it has low support. You can download it from GitHub.

Utils for viewing memory in Swift. 用来窥探Swift内存的小工具.

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Support

Mems has a low active ecosystem.

It has 291 star(s) with 56 fork(s). There are 5 watchers for this library.

It had no major release in the last 6 months.

There are 0 open issues and 1 have been closed. On average issues are closed in 56 days. There are no pull requests.

It has a neutral sentiment in the developer community.

The latest version of Mems is current.

Quality

Mems has no bugs reported.

Security

Mems has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.

License

Mems is licensed under the MIT License. This license is Permissive.

Permissive licenses have the least restrictions, and you can use them in most projects.

Reuse

Mems releases are not available. You will need to build from source code and install.

Installation instructions are not available. Examples and code snippets are available.

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Mems Key Features

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Mems Examples and Code Snippets

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Community Discussions

Trending Discussions on Mems

ELF executable file: many zero bytes

Segmentation fault when replacing `malloc`, `calloc`, `realloc` and `free` via `LD_PRELOAD`

Memory and CPU monitoring via Powershell

Yocto layer for ADIS16475

Is this caused by insufficient memory?

Python - check list membership and store parent group name in a column / multiple lambda statements?

Nim: work with read-only memory mapped files

array members of structs in dart:ffi

When I plot something in python the programs execution stops until I close the plot figure

I'm not able to slice and modify my array to extract desired information out of it

QUESTION

ELF executable file: many zero bytes

Asked 2021-Apr-27 at 18:51

Introduction

I'm compiling a simple assembly code (Intel syntax, x86, Linux) printing "Hello World!". Here it is:

...

ANSWER

Answered 2021-Apr-27 at 18:51

The alignment is 4096 bytes, which is the page size on this architecture. This is not a coincidence, as the man page says about nmagic: "Turn off page alignment of sections".

By the size of the normal (non-nmagic) binary you can guess the linker laid out three pages, presumably with different access (code = not writable, data = not executable, rodata = read only), these rights can only be set per-page. The disk layout matches the layout in RAM when it is running.

This is important for demand paging. When the program starts, the entire executable file is basically mmaped and pages are loaded from disk as needed through page faults. Also pages can be shared between its other running instances (this is more important for dynamic libraries) and can be evicted from RAM when needed due to memory pressure.

The nmagic executable still is loaded into three pages when run, but as those no longer match what is on disk, it is not demand paged. I wouldn't recommend using the option on anything larger.

Note: if you make a longer-running executable (add reading of input perhaps), you can examine the memory layout details of the running process by looking at /proc/[pid]/maps and smaps.

Source https://stackoverflow.com/questions/67288459

QUESTION

Segmentation fault when replacing `malloc`, `calloc`, `realloc` and `free` via `LD_PRELOAD`

Asked 2021-Apr-18 at 16:49

Background

I am experimenting to replace malloc(3)/calloc(3)/realloc(3)/free(3) via LD_PRELOAD environment variable. I have tried to use the customized functions statically linked, they worked perfectly.

But, when I attached it as shared library to LD_PRELOAD, it always results in segfault.

Short technical explanation about functions

I use Linux x86-64 mmap(2) and munmap(2) syscall for malloc(3) and free(3).
The calloc(3) is just a call to malloc(3) with multiply overflow check.
The realloc(3) calls malloc(3), then copy old data to new allocated memory and unmap the old memory.

Questions

What is wrong with my approach so that it always result in segfault?
How can I debug it (gdb and valgrind also segfault)?
What did I miss here?

Note

I am fully aware that always using mmap for every malloc call is a bad idea, especially for performance. I just want to know why my approach doesn't work.

Output ...

ANSWER

Answered 2021-Apr-01 at 06:34

gcc -Wall -Wextra -ggdb3 -shared mem.c -O3 -o my_mem.so

is wrong, if you want to build a shared library. See dlopen(3) and elf(5) and ld.so(8).

You practically need a position-independent-code file, so use

Source https://stackoverflow.com/questions/66898984

QUESTION

Memory and CPU monitoring via Powershell

Asked 2021-Apr-12 at 03:02

I'm trying to monitor cpu and memory usage for a particular process using powershell. The idea is to schedule it and have it get values at specific intervals, then spit them out to .csv.

So far i've run into 2 cases:

The process has a single process ID. Code works fine.
The process has several subprocesses with their own ID. I'd like it to add the values in the final output. I am not interested in the individual values for each subprocess (ex. every single chrome tab) but the cumulative values for all the subprocesses.

This is the desired output: (if a process has subprocesses, the count should reflect that)

...

ANSWER

Answered 2021-Apr-11 at 22:34

I am not sure what your problem is from reading your post. Is it something like this you want to achieve?

Source https://stackoverflow.com/questions/67050007

QUESTION

Yocto layer for ADIS16475

Asked 2021-Mar-26 at 16:58

Context

Lately I've had trouble including an adis driver in my Yocto build. I've asked the question on the adis forum but found the solution before anyone answered it. The adis forum not being very user friendly and the answer being quiet long, I've decided to answer my question here and link it in the forum.

The question

I'm building my OS with yocto and I'd like to add a driver for IMU ADIS1607 (anything but the ease of use is a plus) as part of this build.

I'm building a prototype on a raspberryPi4. My application uses an ADIS IMU (ADIS16507). Since the board for the final product is not fixed I'm building my OS with Yocto.

I'm currently trying to add a driver for ADIS16507. Ideally I'd like to add ADIS16475, but I could do with something else provided it works nicely.

First off I have checked that I'm able to build the whole ADIS linux kernel for RaspberryPi as specified in the doc. With that kernel the driver works nicely.

However the ADIS linux kernel is too heavy for what I intend to do. Hence I'm trying to build a lighter OS with yocto (also, as aforementioned, I'll likely need to port my work on different platforms).

I have a few ideas on how to do it, however none of them worked easily and I'm not sure which one to pursue.

I assumed the simplest way would be to compile the ADIS16475 on its own and add it to the Yocto build. However I'm struggling a little with Yocto and haven't been able to compile sucessfully
Alternatively I did find the libiio layer for yocto but it seems to require quiet a lot of code to on top of it to be able to read the IMU values.
I am aware of the python bindings of libiio layer and of Pyadi-iio and it seems easy to use (although I did not try adding it with yocto) but computational speed is an issue for me and I'd rather use C/C++ instead of python.
Finally I also found the meta-adi layer. I think that in my case it is not relevant but the documentation I found is rather sparse and I'm not certain what this layer is supposed to do.

Any pointer on which method I should use (maybe I've missed an obvious easy one) is welcome.

...

ANSWER

Answered 2021-Mar-26 at 16:58

So here is the solution I found. We will use the ADIS16475 which is a part of the standard libc since version 5.10. Then we'll get the corresponding device tree overlay from ADIS and add the relevant variables to have it compiled with the other device tree overlays.

Getting the correct versions

For this to work we need libc 5.10 or later since earlier version do not include the adis16475.c source file. However only the latest yocto release, Hardknott, uses the 5.10 version. So simplest thing to do is to switch to the Hardknott branch of Yocto. Keep in mind that if you use other layers, you might also have to change release for compatibility reasons.

Configuring the kernel to compile ADIS16475 drivers as built in

Here we're gonna dab into kernel compilation so there are a few things to know

Short and approximate theory

If you don't know much about kernel compilation don't worry, neither do I. But here is an approximate quick explanation in order for you to understand what we're doing: Kernel makefiles hold list of files the have to compile. For drivers there are 2 important ones. obj-y that holds the files that will be built in and obj-m that holds the files that will be compiled as loadable modules. In order to make these list configurable, they are defined in makefiles with statements such as:

Source https://stackoverflow.com/questions/66821241

QUESTION

Is this caused by insufficient memory?

Asked 2021-Mar-19 at 22:17

This problem occurred when I used chipyard to compile Boom. Is this because of insufficient memory? I am running on a 1 core 2G cloud server.

/bin/bash: line 1: 9986 Killed java -Xmx8G -Xss8M -XX:MaxPermSize=256M -jar /home/cuiyujie/workspace/Boom/chipyard/generators/rocket-chip/sbt-launch.jar -Dsbt.sourcemode=true -Dsbt.workspace=/home/cuiyujie/workspace/Boom/chipyard/tools ";project utilities; runMain utilities.GenerateSimFiles -td /home/cuiyujie/workspace/Boom/chipyard/sims/verilator/generated-src/chipyard.TestHarness.LargeBoomConfig -sim verilator" /home/cuiyujie/workspace/Boom/chipyard/common.mk:86: recipe for target '/home/cuiyujie/workspace/Boom/chipyard/sims/verilator/generated-src/chipyard.TestHarness.LargeBoomConfig/sim_files.f' failed make: *** [/home/cuiyujie/workspace/Boom/chipyard/sims/verilator/generated-src/chipyard.TestHarness.LargeBoomConfig/sim_files.f] Error 137

When I adjusted the memory to 4G, this appeared.

Done elaborating. OpenJDK 64-Bit Server VM warning: INFO: os::commit_memory(0x00000006dc3b7000, 97148928, 0) failed; error='Cannot allocate memory' (errno=12)

There is insufficient memory for the Java Runtime Environment to continue. Native memory allocation (mmap) failed to map 97148928 bytes for committing reserved memory. An error report file with more information is saved as: /home/cuiyujie/workspace/Boom/chipyard/hs_err_pid2876.log /home/cuiyujie/workspace/Boom/chipyard/common.mk:97: recipe for target 'generator_temp' failed make: *** [generator_temp] Error 1

Should I adjust to 8G memory, or through what command to increase the memory size that the process can use?

When I adjusted the memory to 16G, this appeared.

/bin/bash: line 1: 2642 Killed java -Xmx8G -Xss8M -XX:MaxPermSize=256M -jar /home/cuiyujie/workspace/Boom/chipyard/generators/rocket-chip/sbt-launch.jar -Dsbt.sourcemode=true -Dsbt.workspace=/home/cuiyujie/workspace/Boom/chipyard/tools ";project tapeout; runMain barstools.tapeout.transforms.GenerateTopAndHarness -o /home/cuiyujie/workspace/Boom/chipyard/sims/verilator/generated-src/chipyard.TestHarness.LargeBoomConfig/chipyard.TestHarness.LargeBoomConfig.top.v -tho /home/cuiyujie/workspace/Boom/chipyard/sims/verilator/generated-src/chipyard.TestHarness.LargeBoomConfig/chipyard.TestHarness.LargeBoomConfig.harness.v -i /home/cuiyujie/workspace/Boom/chipyard/sims/verilator/generated-src/chipyard.TestHarness.LargeBoomConfig/chipyard.TestHarness.LargeBoomConfig.fir --syn-top ChipTop --harness-top TestHarness -faf /home/cuiyujie/workspace/Boom/chipyard/sims/verilator/generated-src/chipyard.TestHarness.LargeBoomConfig/chipyard.TestHarness.LargeBoomConfig.anno.json -tsaof /home/cuiyujie/workspace/Boom/chipyard/sims/verilator/generated-src/chipyard.TestHarness.LargeBoomConfig/chipyard.TestHarness.LargeBoomConfig.top.anno.json -tdf /home/cuiyujie/workspace/Boom/chipyard/sims/verilator/generated-src/chipyard.TestHarness.LargeBoomConfig/firrtl_black_box_resource_files.top.f -tsf /home/cuiyujie/workspace/Boom/chipyard/sims/verilator/generated-src/chipyard.TestHarness.LargeBoomConfig/chipyard.TestHarness.LargeBoomConfig.top.fir -thaof /home/cuiyujie/workspace/Boom/chipyard/sims/verilator/generated-src/chipyard.TestHarness.LargeBoomConfig/chipyard.TestHarness.LargeBoomConfig.harness.anno.json -hdf /home/cuiyujie/workspace/Boom/chipyard/sims/verilator/generated-src/chipyard.TestHarness.LargeBoomConfig/firrtl_black_box_resource_files.harness.f -thf /home/cuiyujie/workspace/Boom/chipyard/sims/verilator/generated-src/chipyard.TestHarness.LargeBoomConfig/chipyard.TestHarness.LargeBoomConfig.harness.fir --infer-rw --repl-seq-mem -c:TestHarness:-o:/home/cuiyujie/workspace/Boom/chipyard/sims/verilator/generated-src/chipyard.TestHarness.LargeBoomConfig/chipyard.TestHarness.LargeBoomConfig.top.mems.conf -thconf /home/cuiyujie/workspace/Boom/chipyard/sims/verilator/generated-src/chipyard.TestHarness.LargeBoomConfig/chipyard.TestHarness.LargeBoomConfig.harness.mems.conf -td /home/cuiyujie/workspace/Boom/chipyard/sims/verilator/generated-src/chipyard.TestHarness.LargeBoomConfig -ll error" /home/cuiyujie/workspace/Boom/chipyard/common.mk:123: recipe for target 'firrtl_temp' failed make: *** [firrtl_temp] Error 137

...

ANSWER

Answered 2021-Mar-09 at 03:23

Short anwer : yes

Error 137 is thrown when your host runs out of memory.

"I am running on a 1 core 2G cloud server"

When you try to assign 8GB to the JVM, OOM-Killer says "no-no, f... no way", and kicks in sending a SIGKILL; This Killer is a proactive process that jumps in to save the system when its memory level goes too low, by killing the resource-abusive processes.

In this case, the abusive process (very abusive, indeed) is your java program, which is trying to allocate more than(*) 4 times the maximum avaliable memory in your host.

Exit Codes With Special Meanings

Source https://stackoverflow.com/questions/66539759

QUESTION

Python - check list membership and store parent group name in a column / multiple lambda statements?

Asked 2021-Feb-10 at 11:22

I have the following lists:

...

ANSWER

Answered 2021-Feb-10 at 11:22

First, create a mapping. You should have been using something like a dict all along, the names of your variables should not contain data. Variable names are for the person reading source code, not the computer. If you need to map strings to other strings, use a dict:

Source https://stackoverflow.com/questions/66135794

QUESTION

Nim: work with read-only memory mapped files

Asked 2021-Feb-06 at 13:08

I've only just started with Nim, hence it possibly is a simple question. We need to do many lookups into data that are stored in a file. Some of these files are too large to load into memory, hence the mmapped approach. I'm able to mmap the file by means of memfiles and either have a pointer or MemSlice at my hand. The file and the memory region are read-only, and hence have a fixed size. I was hoping that I'm able to access the data as immutable fixed size byte and char arrays without copying them, leveraging all the existing functionalities available to seqs, arrays, strings etc.. All the MemSlice / string methods copy the data, which is fair, but not what I want (and in my use case don't need).

I understand array, strings etc. types have a pointer to the data and a len field. But couldn't find a way to create them with a pointer and len. I assume it has something to do with ownership and refs to mem that may outlive my slice.

...

ANSWER

Answered 2021-Feb-06 at 13:08

It is not possible to convert a raw char array in memory (ptr UncheckedArray[char]) to a string without copying, only to an openArray[char] (or cstring)

So it won't be possible to use procs that expect a string, only those that accept openArray[T] or openArray[char]
Happily an openArray[T] behaves exactly like a seq[T] when sent to a proc.

({.experimental:"views".} does let you assign an openArray[T] to a local variable, but it's not anywhere near ready for production)

you can use the memSlices iterator to loop over delimited chunks in a memFile without copying:

Source https://stackoverflow.com/questions/66014574

QUESTION

array members of structs in dart:ffi

Asked 2021-Feb-04 at 16:12

I'd like to use Bob Jenkins rng in my flutter projects https://burtleburtle.net/bob/rand/isaacafa.html

here we have a struct with 2 static buffers in it

...

ANSWER

Answered 2021-Feb-04 at 16:12

Came up with something: keep the original struct but add 2 extra pointers for the buffers

Source https://stackoverflow.com/questions/66048509

QUESTION

When I plot something in python the programs execution stops until I close the plot figure

Asked 2021-Jan-29 at 10:47

This is my code and after calculating some stuff I want it to draw them at each step

...

ANSWER

Answered 2021-Jan-29 at 09:42

plt.show() blocks the execution of your code. To avoid that, you could replace that line by plt.show(block=False). Your application will then run, but, as described in this post, your plots will likely not show up during execution.

So instead, try replacing plt.show() by

Source https://stackoverflow.com/questions/65951965

QUESTION

I'm not able to slice and modify my array to extract desired information out of it

Asked 2021-Jan-23 at 18:23

I wanna read an excel file via pandas.read_excel but the first row is just the indication of the data in the column and I don't want it to be imported. I use this code to skip first row :

...

ANSWER

Answered 2021-Jan-23 at 18:23

I solved this!

Source https://stackoverflow.com/questions/65841211

Community Discussions, Code Snippets contain sources that include Stack Exchange Network

Vulnerabilities

No vulnerabilities reported

Install Mems

You can download it from GitHub.

Support

For any new features, suggestions and bugs create an issue on GitHub. If you have any questions check and ask questions on community page Stack Overflow .

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