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apple-oss-distributions
system_cmds
C2024–2025
apple-oss-distributions / system_cmds

system_cmds

Discover this repository through its Hacker News conversations.

Explore on GitHubRead Hacker News discussions
3Distinct people
3Mentions
0Explicit recommenders
49GitHub stars
REPOSITORY AT A GLANCE

What to know before exploring

What it is

A public description has not been verified.

Where it is used

No documented product use has been verified yet.

What people are saying

No recommendation phrase was found in the indexed comments.

No classified warning is attached to this page. Read the discussions before treating silence as approval.

Also in these discussions

No other repository is repeatedly linked in the same discussions.

This week on Hacker News

Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 3:56:07 PM UTC.

No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.

Mentions over time

HN mentions by month3 dated mentions

Observed mentions: 2024-08-12 00:55:05 UTC to 2025-12-14 19:59:42 UTC.

012024-08-01 00:00:00 UTC to 2024-09-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 commentsAug 20242024-09-01 00:00:00 UTC to 2024-10-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2024-10-01 00:00:00 UTC to 2024-11-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2024-11-01 00:00:00 UTC to 2024-12-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2024-12-01 00:00:00 UTC to 2025-01-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-01-01 00:00:00 UTC to 2025-02-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-02-01 00:00:00 UTC to 2025-03-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-03-01 00:00:00 UTC to 2025-04-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-04-01 00:00:00 UTC to 2025-05-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 commentsApr 20252025-05-01 00:00:00 UTC to 2025-06-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-06-01 00:00:00 UTC to 2025-07-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-07-01 00:00:00 UTC to 2025-08-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-08-01 00:00:00 UTC to 2025-09-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-09-01 00:00:00 UTC to 2025-10-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-10-01 00:00:00 UTC to 2025-11-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-11-01 00:00:00 UTC to 2025-12-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-12-01 00:00:00 UTC to 2026-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 commentsDec 2025

Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.

View mention counts and date ranges
UTC ranges include their start and exclude their end. Select a period to filter the source evidence.
PeriodStart (UTC)End (exclusive, UTC)MentionsSubmissionsComments
Aug 20242024-08-01 00:00:00 UTC2024-09-01 00:00:00 UTC101
Sep 20242024-09-01 00:00:00 UTC2024-10-01 00:00:00 UTC000
Oct 20242024-10-01 00:00:00 UTC2024-11-01 00:00:00 UTC000
Nov 20242024-11-01 00:00:00 UTC2024-12-01 00:00:00 UTC000
Dec 20242024-12-01 00:00:00 UTC2025-01-01 00:00:00 UTC000
Jan 20252025-01-01 00:00:00 UTC2025-02-01 00:00:00 UTC000
Feb 20252025-02-01 00:00:00 UTC2025-03-01 00:00:00 UTC000
Mar 20252025-03-01 00:00:00 UTC2025-04-01 00:00:00 UTC000
Apr 20252025-04-01 00:00:00 UTC2025-05-01 00:00:00 UTC101
May 20252025-05-01 00:00:00 UTC2025-06-01 00:00:00 UTC000
Jun 20252025-06-01 00:00:00 UTC2025-07-01 00:00:00 UTC000
Jul 20252025-07-01 00:00:00 UTC2025-08-01 00:00:00 UTC000
Aug 20252025-08-01 00:00:00 UTC2025-09-01 00:00:00 UTC000
Sep 20252025-09-01 00:00:00 UTC2025-10-01 00:00:00 UTC000
Oct 20252025-10-01 00:00:00 UTC2025-11-01 00:00:00 UTC000
Nov 20252025-11-01 00:00:00 UTC2025-12-01 00:00:00 UTC000
Dec 20252025-12-01 00:00:00 UTC2026-01-01 00:00:00 UTC101

What Hacker News says

3 sources
comex·Apr 6, 2025
The claim is inaccurate and mixes together multiple different things: - The Mach microkernel originally supported true userland paging, like mmap but with an arbitrary daemon in place of the filesystem. You can see the interface here: https://web.mit.edu/darwin/src/modules/xnu/osfmk/man/memory_... But I'm not sure if Darwin ever used this functionality; it certainly hasn't used it for the last ~20 years. - dynamic_pager never used this interface. It used a different, much more limited Mach interface where xnu could alert it when it was low on swap; dynamic_pager would create swap files, and pass them back into the kernel using macx_swapon and macx_swapoff syscalls. But the actual swapping was done by the kernel. Here is what dynamic_pager used to look like: https://github.com/apple-oss-distributions/system_cmds/blob/... But that funct
Read the rest
ionality has since moved into the kernel, so now dynamic_pager does basically nothing: https://github.com/apple-oss-distributions/system_cmds/blob/... - The vast majority of kernel memory is wired and cannot be paged out. But the kernel can explicitly ask for pageable memory (e.g. with IOMallocPageable), and yes, that memory can be swapped to disk. It's just rarely used. Still, any code that does this needs to be careful to avoid deadlocks. Even though userland is no longer involved in "paging" per se, it's still possible and in fact common for userland to get involved one or two layers down. You can have userland filesystems with FSKit (or third-party FUSE). You can have filesystems mounted on disk images which rely on userland to convert reads and writes to the virtual block device into reads and writes to the underlying dmg file (see `man hdiutil`). You can have NFS or SMB connections going through userland networking extensions. There are probably other cases I'm not thinking of. EDIT: Actually, I may be wrong about that last bit. You can definitely have filesystems that block on userspace, but it may not be supported to put swap on those filesystems.
In Apple’s Darwin OS and XNU Kernel Deep Dive
justinclift·Aug 12, 2024
> Memory pressure is an internal macOS system metric Interesting. That'll probably mean it's in the source code Apple publishes for macOS: https://github.com/apple-oss-distributions/distribution-macO... Doing a search for the phrase "memory pressure" in the containing organisation (apple-oss-distributions) shows some relevant stuff: https://github.com/search?q=org%3Aapple-oss-distributions+%2... • memorystatus.md : https://github.com/apple-oss-distributions/xnu/blob/94d3b452... # Memorystatus Subsystem Dealing with memory pressure by forcibly recovering pages. (etc) • memory_pressure.1 : https://github.com/apple-oss-distributions/system_cmds/blob/... Looks like the man page for a `memory_pressure` command • freezer.md : https://github.com/apple-oss-distributions/xnu/blob/94d3b452... # Freezer Details of how so
Read the rest
me processes can be swapped out to disk. [...] The freezer is a limited form of swap on embedded. Under memory pressure, the freezer picks apps to freeze. (etc) And a whole bunch more. With some digging, it should be possible to find the exact info. :)
In MacBook Air, M2 Chip, 8GB RAM: Nothing is open, but half the memory is gone

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