Re: [PATCH] mu: Add a new tool to show memory usage of files

[Rob Landley]

On 2/19/25 11:24, Bernhard Voelker wrote:
> On 2/10/25 2:34 PM, Matteo Croce wrote:
> > mu is a new tool which shows the amount of data that a set of files
> > are keeping into the cache.
> > mu uses the new cachestat() syscall introduced with Linux 6.5.
>
> The GNU coreutils aim to be a platform independent implementation of a 
> certain
> set of tools, most of them specified by POSIX.

Busybox has a "readahead" command under miscutils, which preloads a file 
into disk cache. This seems like an option to readahead. (Maybe -s to 
show size?)

> As 'mu' seems to be bound to the GNU/Linux kernel and the particular 
> cachestat() syscall,

The "GNU/Linux kernel"?

So Stallman's explicitly claiming the Linux _kernel_ now?

> it seems to be impossible to provide the same functionality under other 
> kernels and platforms.

People have implemented multiple compatible kernels running linux 
syscalls. Standalone things like https://github.com/vvaltchev/tilck but 
more often API layers: Microsoft's WSL 1.0 was basically Wine backwards, 
FreeBSD's Linuxulator has been doing it for 20 years, Solaris had Linux 
Zones, the L in AIX 5L stood for "Linux Affinity" (IBM's name for binary 
compatibility), QEMU's application mode is bidirectional translation of 
each individual syscall... Heck, the 86Open project (a big multi-vendor 
effort back in 1997 to create a common Intel Unix binary format) gave up 
and declared "just use lxrun with linux binaries" back in 1999: 
https://web.archive.org/web/20010424134601/http://www.telly.org/86open/

Luckily util-linux and friends exist to host commands gnu/coreutils 
doesn't want to. And busybox. And toybox. Heck, Chimera Linux uses BSD's 
userspace on a Linux kernel. (Linux has always been about modularity. 
Interchangeable parts available from multiple sources, you can use 
dropbear instead of openssh, etc.)

I still think readahead -s makes sense here. You can tell Denys I said 
so if you like. :)

Rob