MacOS succeeded the classic Mac OS, a Macintosh operating system with nine releases from 1984 to 1999. During this time, Apple cofounder Steve Jobs had left Apple and started another company, NeXT, developing the NeXTSTEP platform that would later be acquired by Apple to form the basis of macOS. What is the equivalent of such thing in Mac OS (and iOS)? I am aware of the sysctl interface, but it does not appear to provide the equivalent information. I have looked at the 'top' output (invoked by non-root user) on Mac OS and it contains things like. RPRVT - amount of resident memory consumed by our heap allocations. Maximum Memory: The'Unibody' MacBook Mid 2010 has a system maximum of 16GB (2x 8GB SO-DIMMs) if you are running OS Lion (10.7) or above. MacBook Memory for Model 6.1: MacBook Late 2009 DDR3-1066Mhz. Maximum Memory: The'Unibody' MacBook Late 2009 and newer have a system maximum of 8GB. In OS X, the virtual memory system often writes pages to the backing store. The backing store is a disk-based repository containing a copy of the memory pages used by a given process. Moving data from physical memory to the backing store is called paging out (or “swapping out”); moving data from the backing store back in to physical memory. This is a quick way to have easy visual access to your memory usage without having to rely on a Dashboard Widget, or even have Dashboard running for that matter. And you don't have to download anything. This comes standard with every new Mac running OS X. Being involved with web design, and design in.

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As I'm currently rewriting Q - [kju:] from scratch, I have to tackle a longstanding QEMU frontend problem: vga buffer of the guest os in one application - vga output window in a viewing/controlling app.
The most economic would be a buffer that could be accessed by both apps. Shared Memory.
There was once a shmem patch submitted to the QEMU dev list, but it got dropped in favor for a vnc solution. As I'm not satisfied with vnc speed, I took a stab at the shmem patch.

shmem on OS X, it's a no-go...
Shmem would be the most geleagnt way of creating shared memory. Unfortunateley, Apple has limited shmem to a lousy 4MB - for the whole system!Blade:~ mike$ cat /etc/rc grep shmmax
sysctl -w kern.sysv.shmmax=4194304 kern.sysv.shmmin=1 kern.sysv.shmmni=32 kern.sysv.shmseg=8 kern.sysv.shmall=1024Manipulating rc is not my thing. Setting shmem with 'sysctl -w kern.sysv.shmmax=10485760' to 10MB on the fly needs to much privileges.

Distributed Object, anybody?
I'm already using DO to communicate between the controoling ap and the QEMU instances. The problem with DO is, that all the messages are copied and sent to the corresponding object. So accessing a buffer in a distandt object with - (void *) screenBuffer; will copy and send the whole buffer, not just a memorypointer. The advantage of the DO, you could have the viewer on a different machine - (Q - [kju:] Server anybody? :)).
So I wrote a methode, that just sends updated segments of the screenBuffer.
Here is a downstripped version of the Distributed Object (DO) I used to transfer changes in the guests videoram to the viewer:

DO in data reciever process:

DO in data creator process:

Downside of the shared Object: data is copied at least 2 times: when the message is created and when the data is writen from the message to the reciveers buffer. Faster than vnc... but data objects are sometimes not released as fast as created => incredible memory footprint.

finally, mmap!
With mmap you can load a file into memory. If more than one processes mmap the same file, all processes can access the same mmap, that way we have shared memory, and a convenient way to share the adress: the file.

First we need a file the size we need shared memory...

Mac Os Mojave

...after we attach, from multiple processes.

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Downside? Well if more than one process make changes to the mmaped file, it's writen from time to time (normally when the last process exits) but I can live with that.
I hope to comit the rewrite of Q - [kju:] soon 🙂

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Mike