Possibly Dangerous Performance Tweaking

[vbgunz]

ram + logs + ~/.kde ... a recipe for nuisance or catastrophe, your call. There are upsides and downsides to letting it simply be or putting it all onto a ramdisk. The upshot to the ramdisk approach is performance beyond-compare* (correct)? The dark-side of it is either a crash, power outage or unclean shutdown of any sort can cause major data loss/corruption...

Can we agree on the up and down here? If not maybe its all about a non-problem. If so, could there possibly be a compromise/alternative approach that is safe and performance rooted? I can see the benefits and the horror. Something about the benefits though really urge me to look into it. I cannot personally remember the last time I looked into any logs. I also cannot remember the last time I went through an unclean shutdown on my current system. I am a bit intrigued about it, see my reasoning?

I might just be onto nothing here so I am asking. What exactly could be expected of a system if directories like /var/log and ~/.kde were stored in RAM? Would flushing the RAM every couple of minutes actually be worse than no ramdisk at all, or will such a compromise be necessary to get the best of both worlds (performance and integrity)? I'd really like to hear what some folks (especially from those who know better) think/know about this.

Thank you for your time!

PS. Spirited/informative debate? Knowledge?


--
* Doesn't mean Vs a brand new 38 128bit core processing chip with 400 trigabytes of SSD, etc. Simply means, Vs anything else you can do with the following directories on the same machine.

[dibl]

Re: Possibly Dangerous Performance Tweaking

I will risk my membership here and simply mention that there is a Debian distribution (sidux) that offers, on its Live CD, the option to install it on a USB stick with "fromiso", "toram", and "persist" boot options enabled. Believe it or not, it was under 10 minutes elapsed time to do just that (about 6 months ago). So now I have this 4G USB stick and if I put it in any PC that I have found, and set the BIOS to boot from USB first, up pops a full-featured sidux operating system, running in RAM -- it's got OOO, Konqueror -- all of KDE 3.5 right there, and not touching the hard drive. With "persist", you can set up your browser tabs and home page, save documents, and everything, and it is retained on the system. It's very cool, but of rather limited utility unless you are in the PC repair business or something like that.

That kind of setup may well be possible with Kubuntu -- I dunno. But I'll bet it's more that clicking a couple of buttons on the Live CD. :P You could probably come close by starting here and then working with Qqmike's guidance here:

http://kubuntuforums.net/forums/inde...opic=3089474.0

In the main, I'm more of an advocate of buying the CPU, RAM, and hard drive that you really want, if performance is a big deal for you. And oh yeah there's these tips too.

[Troberg]

Re: Possibly Dangerous Performance Tweaking

Without actually knowing how to achieve it, I think that what you need is probably a huge disk read cache. That would give you the speed you want without the risk.

[tinker]

Re: Possibly Dangerous Performance Tweaking

I'm going to stick my neck out a bit too but I don't imagine we will risk being run out of town as I don't think anyone here wants to switch people away from Kubuntu. Kubuntu is probably more newbie friendly than most other distros, but that's just my opinion.

One thing dibl didn't mention about the distros that can be optioned to run in RAM (Sidux is only one of them) is that, even on the off chance that your system is compromised while you are online, when you shutdown, if you aren't using persistence, everything is gone and the next boot is a clean system. In addition, you haven't left traces of surfing or other activities behind.

Sidux (like Kubuntu) is based on Debian Sid, "unstable" and thus also has more of the newest features and eye candy that users like to have. Those developers do a good job, just like they did when they were associated with Kanotix.

I'm not sure that you necessarily want something like .kde on a RAM disk if you get a power outage. As to your not looking at logs, well, a log might be useful after a crash if you care to troubleshoot the crash, I want them saved to inspect, but we have choice.

You could also gain performance by using a flash disk instead of a HDD and this could be the best choice for certain situations. You'll probably get more "performance" by increasing RAM than relocating folders and with less "risk". What is actually best for your system is tied very closely with how you use it and what you do with it, more so than whether you are using up available RAM with ram disks. It seems to me that there could be better uses for RAM than storing logs which only get written to occasionally unless there is some problem. and, as I mentioned, I want those logs available after a crash if possible.

But hey, try it and come back with the results, that could help to instruct us all, it would give us data to work with. Someone probably could help you refine your method.

[vbgunz]

Re: Possibly Dangerous Performance Tweaking

dibl, the responsivenessland article you linked to is quite an interesting read. I truly believe the perceived responsiveness is ridiculously important on the desktop. I don't mind if what I want done takes a few seconds/minutes as long as what I do appears at the whim of a click/command. nice. thanks

Troberg, I am by far the sharpest tool in the shed. I actually looked into *resizing* the cache and have come to the conclusion that is is only possible with a hardware upgrade. Thanks for the tip

tinker, Putting /tmp, /var/logs, ~/.kde on a ramdisk was an *idea* that stems from the idea that RAM should probably be one of the fastest pieces of storage hardware on the modern PC. 9 out of 10 would probably say, the cheapest, fastest and simplest way to upgrade a PC is to upgrade the RAM. So, I thought, why not dedicate a portion of it to some things that read/write constantly?

Heh, I've been reading about it and well, technically if it isn't confusing at best it sure is a paradox. about 1 out of every 2 articles I read on the subject says don't do it. This is why I asked here on Kubuntu forums. I was hoping maybe someone had some thought or knowledge about it and would like to share some ideas/tips/facts about it.

I am aware of the pitfalls but am also very interested in the possible benefits and was hoping for a decent/possible compromise that would sort of address the best of both worlds. I'll keep looking into it but at this rate I may simply give up on it

[Troberg]

Re: Possibly Dangerous Performance Tweaking

There are several levels of disk cache. One is on the disk, and that is not something you can change. Another may be in normal memory, controlled by the OS, and that might be changable. Then, there are probably some minor caching on the PCI bus, but that's not important here.

[dibl]

Re: Possibly Dangerous Performance Tweaking

There's been some interesting use of "efficiency" techniques posted on the Eee PC forum, due to the fact that it comes with a 4GB SSD, and no hard drive, and also that it has a built in SD card reader that is, in actuality, a USB interface. So folks do all kinds of tricks to get a decently-performing OS and some storage space working. For example, I set mine up to automatically boot up with /home on a 16GB SD card mounted in the card reader.

As said by tinker, there are slax and other OSs that are optimized to do what you are looking at. Here are some links that may be interesting for you:

http://forum.eeeuser.com/viewforum.php?id=15

http://www.slax.org/