The core part of an operating system, responsible for managing resource allocation.
Questions tagged [kernel]
220 questions
665
votes
13 answers
How to find cause of high kernel_task cpu usage?
Occasionally my machine will have a kernel_task instance max out the CPU:
This can last from minutes to sometimes hours. The machine is effectively unusable in this state. Restarting doesn't help; a new kernel_task pops up again until it finishes…
Adam
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148
votes
2 answers
How to investigate high kernel task memory usage?
I was using my MacBook Pro (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 you are not using.
I've obviously closed few…
kenorb
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55
votes
1 answer
Why is macOS limited to 1064 or 2088 processes?
In macOS, the system is limited to running no more than 1064 processes (or 2088 starting with Catalina) systemwide, and individual users are limited to 709 (or 1392 in Catalina). Why is there a limit? Why is it this size? Why not a round number like…
Old Pro
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46
votes
3 answers
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 were playing videos, but Safari’s CPU usage was…
theorist
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37
votes
3 answers
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?
Tuesday
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31
votes
6 answers
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, otherwise, my computer would not properly turn on (MacBook…
Arthur
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22
votes
4 answers
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
"Too many open files" is apparently a common error on…
keflavich
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22
votes
2 answers
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 checked memory use, only to find this:
The…
houbysoft
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16
votes
3 answers
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 what would happen?
From what I understand, Unix…
DrWongKC
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16
votes
1 answer
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.
How do I find what fds are used by a process?
theTuxRacer
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15
votes
3 answers
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.
Thomas Vogler
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14
votes
3 answers
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.AmbrosiaSW.AudioSupport or…
Jan Fabry
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14
votes
3 answers
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 I can increase the setting in Lion?
I found…
Michael Stum
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14
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4 answers
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/xnu-2782.20.48/bsd/kern/kern_exit.c:363
uuid…
Jessa
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13
votes
2 answers
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 physical memory?
See:
Visualization in testing a…
kenorb
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