| inetpro | ahoi ubuntuland! | 15:42 |
|---|---|---|
| === Maaz_ is now known as Maaz | ||
| theblazehen | hi inetpro | 15:47 |
| inetpro | theblazehen: how are you doing? | 15:47 |
| theblazehen | Good and you inetpro ? | 15:47 |
| inetpro | all good thanks | 15:47 |
| inetpro | theblazehen: what can you tell me about running virtual machines with 32bit Ubuntu server on a 64bit KVM host environment? | 15:59 |
| inetpro | good idea / bad idea, or does it even make a difference? | 15:59 |
| theblazehen | inetpro: Depends on workload inside the VM | 16:02 |
| theblazehen | I'm assuming you won't be needing more than 4 GiB RAM inside the guest? | 16:03 |
| theblazehen | 32 bit will use 32 instead of 64 bit pointers, so less overhead there, but misses out on cool x64 features | 16:04 |
| theblazehen | Check out that top bit of https://en.wikipedia.org/wiki/X32_ABI for a TL;DR | 16:04 |
| MaNI | ubuntu doesn't use x32 though does it, just standard x86 (i386)? | 16:15 |
| MaNI | note also that x32 (which sadly probably isn't what you will get) only limits to 4GiB per program, so you can still use more than 4GiB in total | 16:19 |
| inetpro | if I just need a server with less than 2GB of RAM surely 32bit will be more effective on resources? | 16:19 |
| inetpro | s/effective/efficient/ | 16:20 |
| MaNI | sure, but if it's x86 it wastes half the registers and a bunch of other fancy cpu capabilities | 16:23 |
| MaNI | x32 is meant to be the compromise between the two - but I'm unaware of any mainstream binary distro offering it as an option | 16:23 |
| inetpro | hmm... and most developers now have 64bit, so I guess 64bit is probably safer to go as well? | 16:24 |
| MaNI | I would not expect much difference in terms of stability at this point | 16:28 |
| MaNI | either way | 16:28 |
| inetpro | thanks for the inputs | 16:32 |
| theblazehen | "ubuntu doesn't use x32 though does it, just standard x86 (i386)?" MaNI Yeah, wasn't recommending it, it just had a great TL;DR of the (dis|)advantages of each | 16:32 |
| inetpro | am not sure what exactly is in this ISO ubuntu-14.04.5-server-i386.iso | 16:33 |
| theblazehen | inetpro: That's normal 32 bit | 16:34 |
| inetpro | I have a machine with that running, how do I check? | 16:34 |
| MaNI | i386 = normal 32 bit indeed | 16:34 |
| theblazehen | `uname -p` | 16:34 |
| inetpro | i686 | 16:35 |
| MaNI | short version. x86 (i386/i486/i586/i686) can have smaller binaries and less memory but uses less of the CPU | 16:35 |
| MaNI | x86_64 uses all of the new cpu features, but often makes programs use more memory | 16:35 |
| MaNI | x32 is meant to be the best of both worlds but isn't really available for anyone who isn't a cutting edge power user to use | 16:36 |
| inetpro | MaNI: yah, that last point is the big problem going forward | 16:36 |
| MaNI | despite the above there are certain workloads where x86 can outperform x86_64, but for the most part x86_64 will perform better YMMV | 16:37 |
| theblazehen | 👍 Nice summary MaNI | 16:37 |
| MaNI | x86 binaries also tend to suffer in that they are built for the 'lowest common denominator' of x86 cpus - and x86 cpus date very far back. So they often don't take full advantage of some of the new x86 cpu features even... While x86_64 does not have such a long history so x86_64 binaries make use of more modern features | 16:39 |
| MaNI | but people who compile for themselves like myself can side step this (for example) - so it's hard to get proper comparisons even when you look at benchmarks etc. | 16:40 |
| theblazehen | afaik programs can do feature detection, and use faster instructions if they are available? | 16:41 |
| MaNI | some can certainly | 16:42 |
| MaNI | and especially things like video compression libraries generally do, much like facebook relationships "it's complicated" :( | 16:43 |
| inetpro | haha | 17:00 |
| NeRoboto | Ubuntu! | 18:26 |
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