Questions tagged [kernel]

The core part of an operating system, responsible for managing resource allocation.

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128
votes
2answers
177k views

How to investigate high kernel task memory usage?

I was using my MBP (with 16GB of RAM) as usual and out of blue I've this popup that: Your system has run out of application memory. To avoid problems with your computer, quit any applications ...
46
votes
3answers
13k views

AppleCare engineer says Macs need weekly reboots b/c “kernel expires”. What's that mean?

I'm running MacOS Sierra on a mid-2014 MacBook Pro. About once/week, Safari’s CPU usage becomes very high, and it becomes very laggy. In the last instance I had just six windows open, none of which ...
30
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3answers
56k views

What exactly does kernel_task do?

I'd just like to know what it is that kernel_task is responsible for. Also, what's an acceptable maximum RAM and CPU use for it?
27
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6answers
62k views

How to disable the SpeedStep when using MacBook Pro without a battery?

First of all, the specs: MacBook Pro (15-inch, Early 2011) OS X 10.9.1 (Mavericks) 2.3 GHz Intel Core i7 8 GB RAM The Problem Recently, my battery randomly died and I had to disconnect it, ...
21
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2answers
11k views

Insanely high kernel RAM usage (over 9GB) in Mavericks

I upgraded to Mavericks yesterday, and everything seemed to go fine, but today I noticed that my computer was becoming a bit slow. I checked Activity Monitor, and CPU / disk were at normal levels so I ...
19
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4answers
10k views

Which command controls the open file limits?

Which command / configuration file controls the open file limits on OS X? Is there a different command for OS X 10.5 / 10.6 / 10.7? The options I explore below are ulimit, sysctl, and launchctl "...
17
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3answers
9k views

What does it mean for consumers that Apple has released MacOS kernel as open source?

https://techcrunch.com/2017/10/01/apple-open-sourced-the-kernel-of-ios-and-macos-for-arm-processors/ Does this mean we'll see other Computers (which are not Apple built) run the MacOS? If not, then ...
13
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3answers
11k views

What is a Kernel Panic and what does it mean?

I have this report: Anonymous UUID: Removed Tue Aug 11 20:26:13 2015 *** Panic Report *** panic(cpu 2 caller 0xffffff8028bc1cde): "launchd died\nState at Last Exception:\n\n"@/SourceCache/xnu/...
12
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2answers
8k views

kernel_task filling up disk

Something weird just happened. I got a warning that my disk was running out of space. I knew that it had like 15GB free before and wondered where all the free space went. I checked Activity Monitor ...
11
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2answers
2k views

How to access /dev/mem in OSX?

How I can access /dev/mem (or /dev/kmem, /dev/pmap) equivalent device in OSX? As far as I know it was removed in some point. Can I create this node manually somehow or any other way of dumping the ...
11
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2answers
3k views

Why does leaked memory appear malloced to kernel_task, and why can't OS X therefore garbage collect it

I have previously been told that a sign that some application has a memory leak is that kernel_task has a large memory footprint, commonly on the order of gigabytes. If an awry kext was causing this ...
11
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2answers
4k views

Is integrated VRAM included under `kernel_task` RAM in Activity Monitor?

I was stunned to discover that Mac OS X kernel can consume 750MB of RAM. A few related questions: Is it a problem if kernel_task is routinely above 130MB on mid 2007 white MacBook? kernel_task using ...
9
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1answer
6k views

How to unload kernel modules

When I run kextstat, it gives me a list of the currently loaded kernel modules. How to I go about using the information gathered from this command to unload a kernel module?
9
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2answers
12k views

Where can I download the Darwin 12.2.0 source code?

I'm wondering where I can download the source code of the kernel of Mac OS X Mountain Lion 10.8.2: Darwin 12.2.0. I googled it, but its hard to find. And yes, I tried http://www.opensource.apple.com.
9
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1answer
12k views

Sleep Wake Failures because of watchdog on 10.13 (supplemental update)

I have experienced this twice in the last 48 hours, both occurring around the same time. Are the times correlated or coincidence? Can anyone shed some light on this for me? Relevant lines from system....
9
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1answer
8k views

OS X's “free” or “/proc/meminfo” equivalent

OS X lacks the "Linux-friendly" free or /proc/meminfo. What would be the most reliable and backwards-compatible way of extracting this info: Current free memory, in bytes Going back as far as ...
8
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2answers
4k views

What's the maximum pid for Mac OS X?

The Mac OS X Internals book states that the maximum process identifier is 30,000 and after that the kernel will start re-using pids. But checking on my own system, via: ps a | grep ps | grep -v grep ...
8
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1answer
5k views

Why doesn't /proc exist in OS X?

What is the reason that /proc does not exist in OS X? I was curious to find file descriptors that a process was using in my Mac. The way I do it in linux is to go in /proc/fd folder of that process. ...
8
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3answers
7k views

How to properly increase a `ulimit -n` limits?

I'm trying to download the X-Plane 10 Demo through uTorrent, however I get a "too many open files" error all the time. I can do the alternate download (which takes forever and a day), but I wonder how ...
8
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0answers
94 views

Does macOS still use Yarrow as it's cryptographically secure pseudorandom number generator?

I'm trying to understand if the XNU underpinnings of macOS (BSD) still use the Yarrow cryptographically secure pseudorandom number generator? I have looked through the source and it seems as if they ...
7
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2answers
6k views

How to disable logging to system.log in OS X?

During my time with Yosemite, I've had an innocuous issue that gets logged to system.log non-stop. This question is not about solving the issue. I'd like to stop the chatter, because they're writes ...
7
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1answer
3k views

How can I increase the maximum allowed swap space?

When I try to do a calculation that needs to allocate and use 128 GB of memory (it is a command line program written in C), the kernel kills my process with extreme prejudice. This console log entry ...
7
votes
6answers
19k views

Very high kernel_task CPU usage after updating to Yosemite 10.10.4

I updated to 10.10.4 on July 1, and ever since I've had very high CPU usage - roughly 270%, i.e. two and a half of four processors - by kernel_task. It appears on login for about five minutes, then ...
6
votes
1answer
9k views

How to find what cause Mac OS kernel panic?

For last times i have kernel panics at least once a day. Anyone have suggestions how i can find what cause issue and how to fix it? I have latest Yosemite updates installed. Here is latest Problem ...
6
votes
3answers
8k views

Where to see kernel startup messages after boot?

I set my kernel to boot up verbose using sudo nvram boot-args="-v" These logs are what I wanted to see, but how can I view the log after booting? I searched all log files without success.
6
votes
1answer
6k views

How do I increase “ulimit -u” (max user processes)?

I can change all of the usual ulimits via (for instance) ulimit -n 8192 and launchctl limit maxfiles 8192 8192. Somehow, this doesn't seem to work for -u, the maximum number of user processes: ~$ ...
6
votes
1answer
3k views

CPU stuck at 0.8Ghz on iMac late 2013 2.7Ghz because of kernel_task

I know it seems like this question is like the dozens of other questions about CPU overheating and kernel_task overloading it, but nope. I found an iMac (yep, found it. In the trash). I fixed it (...
6
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3answers
1k views

How to get a mac to wait longer for external disk to wake up upon resuming from sleep?

My Mac has an external disk attached, and I often get "disk not ejected properly" warnings after resuming the computer from sleep. These warnings appear only when the disk has spun down during the ...
6
votes
2answers
11k views

File location of kernel extensions?

Is there an easy way to make the mapping from kernel extension to the file it came from? I can get the list of currently loaded kernel extension via kextstat. This gives me the bundle names, like com....
6
votes
0answers
2k views

Is there a way to generate a kernel core dump file after a kernel panic occurred on OSX?

I need to debug a kernel panic and the current information in the kernel panic log file is insufficient. The only information available on that matter is in the following link: https://developer....
5
votes
2answers
1k views

Inspecting kernel_task

I have two MacBooks, one with a fresh OS X install and one with an older install. The older one has a kernel_task taking 1.52 GB of RAM. The newer one—416 MB. These aren't identical machines or ...
5
votes
1answer
1k views

How can I identify files and programs connected to the kernel_task process in Mac OS?

I understand that the kernel_task process is linked to several .kext files found in System/Library/Extensions (and possibly Library/Extensions ?) How can I identify which files are contributing to ...
5
votes
1answer
1k views

Can OS X dump cores in the working directory instead of /cores?

I don't know when it started, but at some point, OS X started dumping cores into a special folder (/cores). This is a pain since they get jumbled together and it's hard to keep track of which core ...
5
votes
1answer
6k views

Is there perf profiler tool for Mac to trace all page faults?

I'm looking to install perf which is a kernel profiling tool for Linux. Basically I'm trying to trace all page faults, so I run equivalent of: sudo perf record -e page-faults -ag Is it possible to ...
5
votes
1answer
81 views

What is this security feature called?

What is this "System software from developers" security feature called and where can I find the technical details for how it works with applications (like AVG)? I believe this is a kernel extension, ...
5
votes
0answers
189 views

Fake ethernet interfaces (feth / if_fake)? Anyone ever seen this?

I've been digging into Darwin source to try to find some way to create virtual Ethernet interfaces on Mac/Darwin without adding a kernel extension like tuntaposx. In doing so I've found something ...
4
votes
3answers
12k views

Why won't kern.maxfiles setting in /etc/sysctl.conf stick?

I've been getting various "too many files open in system"-type errors on Yosemite (10.10.1). Searching around suggests setting kern.maxfiles and kern.maxfilesperprocess in /etc/sysctl.conf. I've ...
4
votes
5answers
8k views

macOS Sierra, kernel_task running taking more than 400% of CPU

After upgrading my MacBookPro to macOS Sierra, CPU is running very fast. When I tried to debug the issue, here is what I have found. Solutions that I have already tried. Reset SMC Reset PRAM Tried ...
4
votes
1answer
3k views

kernel_task Virtual Memory Size too high

I'm using MacBook Pro ("Core i7" 2.5 15" Mid-2015 (DG) 2.5 GHz Core i7 (I7-4870HQ) 16GB RAM) with MacOS Sierra 10.12.4 on it. After connecting a new LG 34UC98 Monitor I faced some heat problems and ...
4
votes
2answers
3k views

What happens when the kernel_task is killed?

What happens when you kill kernel_task on OS X? Is that even possible? I know that the system reboots because of kernel panic when you kill launchd, but I can't find any resources online and am afraid ...
4
votes
1answer
3k views

Keep getting this kernel panic

I keep getting this kernel panic once a week and a half roughly. It freezes the computer (2010ish 17" MBP), showing this error: And giving this error dump on reboot: Interval Since Last Panic Report:...
4
votes
1answer
3k views

What's a normal value for kernel_task RAM usage?

Just bought a new MacBook Pro 12.1, early 2015 (Yosemite 10.10.4). I'm observing memory usage from kernel_task varying between 0.8-2.0 GB. Is it normal? Couldn't find a question referring to normal ...
4
votes
1answer
903 views

How to debug “too many open files”?

I have a program that quits after a time with "too many open files". How can I trace which files are opened and closed? I know I can set this limit a higher value, but that would only defer the ...
4
votes
3answers
2k views

I see thousands of these in my Console log

8/5/11 5:21:37 PM kernel FireWire GUID ffffffffffffffff is invalid! I have a Macbook Pro Core 2 Duo running Snow Leopard. Any suggestions?
4
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2answers
6k views

How to disable SpeedStep/XCPM on Macbook Pro 11,1 OSX 10.10.2?

Does anybody know how to disable OSX from throttling/underclocking the CPU on a Macbook when the battery gets low on power? I think the feature is called SpeedStep. The problem is that my battery is ...
4
votes
1answer
1k views

MacBook unusable due to kernel_task

I've disabled hibernation, and removed the sleep image file. I shutdown my Macbook Pro (15" retina), unticked the box to open windows on restart, and started my MacBook again. As soon as I'd logged on ...
3
votes
3answers
988 views

Interesting Mac OS X error

Has anyone ever seen an error like the one pictured below on Mac OS X? What is it? The system is 10.6.6. I'm quite experienced in OS X but I've never seen such a thing. I was booting in verbose modem, ...
3
votes
4answers
4k views

How to know my kernel extensions are 64-bit ready?

Is there an easy way to tell whether all my kernel extensions will "survive" booting with a 64 bit kernel? I can of course try the "6-4 finger boot", but maybe there is a piece of hardware I use ...
3
votes
3answers
11k views

Kernel panics; Apple hardware test error codes… Bad memory?

My MacMini, which I bought new around Thanksgiving 2010 from Amazon, has been having quite a few kernel panics. They aren't consistent in any way, but they have become more frequent and now many apps ...
3
votes
2answers
2k views

Why kernel log is empty?

My macOS 10.12.3 crashed while suspended and I want to look in the log files to determine where the problem comes from. I opened System Information and in the Logs I found a Kernel log entry linked ...