SimpleX, cURL / Tor, Linux / RAM Usage

1. SimpleX Chat client should allow a light essential metadata backup mode, where everything else, except the contact information and key configuration is left out of the backup. Backing up messages, images, and attachments is mostly pointless.

2. Watched latest SimpleX Chat Live Talk @ Monero Konferenco 4 - Praha - 2024 - Notes: Lot's of references to old posts and comments. Quite likely there won't be anything new, except maybe some reveals at the very end. Yeah, only old slides, we've all seen earlier.

3. With Matrix you can set the rekeying interval freely, by configuring rotation time and count for room messages. So there's no fixed key rotation time and nor number of messages. The defaults for rekey are 7 days and 100 messages. 

4. The Tails OS (@ tails.net) is now writing to the boot media random number seeds (@ tails.net). Is that good or bad? - At least it reveals when it was used (?), unless special counter measures (which might be ineffective) have been taken.

5. Strange discussion if socks5 and DNS  lookups should work differently based on cURL's internal TLD list. - I personally prefer programs, which work consistently. If you start doing endless exceptions and assumptions based on things then you'll end up with program which becomes much harder to explain something quickly and accurately. This then leads to the situation where you’ll have to test and debug every new case or read the source code to gain knowledge of how the program works, because it can’t be simply and shortly explained. And when the TLD exception list is updated, it changes the behavior of existing setups, which can also be surprising at times. (Of course, this is nothing new, especially to you. But see it just as a generic comment). - All of this, of course, is just a personal opinion based on my personal experience with many projects trying to follow KISS. - P.S. I’ve used cURL a lot with Tor and I2P, and so far I’ve been happy with the --socks5-hostname and --resolve options. These options allow you to use socks5 for DNS resolution and or specifying specific DNS resolver like Tor's resolver port. - What am I missing here? Maybe something essential, I just don’t know what. - Discussion started from point that cURL (@ curl.se) may leak .onion domain information to DNS server... If it's uh oh, configured insecurely by a user whom doesn't know how to use it correctly.

6. Another strange discussion about programs "RAM usage" and or "how much ram it needs". Old school classic RAM example - First, I run a program that roughly allocates and fills 3 GB of RAM. - RSS: python3 3156956 - Then, I run a second instance of it. Wait for a while, and now - python3 1044036, python3 2380900 - Neither of the programs has released any RAM. But the RSS is now roughly half of the RAM that the programs are using. But why? Well, that's just because the rest of the stuff is in swap and not included in RSS anymore. Does it mean that program "uses" or "needs" less memory? - I've found out that memory is one of the most misunderstood concepts with modern operating systems. And that's probably because it's a very complex topic. I really don't know anything about it, but over the decades, I've tried to get even the most important stuff right in my mind, because I've dealt a lot with VMs that had very limited RAM and high memory loading at least for short periods of time. - I often hear sysadmins, DBAs, and users claim that the system is just running out of memory, and they're panicking and asking to get more memory before the system crashes. I just log in, run a program that allocates 4 - 8 gigs of RAM, fills it, holds it for a moment (optional), and then releases it. And whoa, now we've got N gigs of free RAM on a system that was supposedly out of RAM?! - So, when the system is out of memory, just run this to reserve N gigs of more RAM and reduce the RSS of other programs. (Yes, I used the 3 GB version for this demo, but I've bumped it up to 4 GB.) - `py -c "grab_it = b' ' * 4 * 1024 * 1024 * 1024"` - Of course you can use whatever language or memory reservation scheme you like instead of Python. - And to Jarkko, and for sure, I do realize that you're posting from kernel.org, which scares me. What's the most important thing I've missed in my post and got completely wrong? The VMs I've dealt with are mostly Windows, but basically behave quite similarly to Linux. Btw. Memory mapped huge files are great way of creating "permanent out of ram" situations, where free memory seems to be very low.

2025-01-19