I\’ve always wondered what the performance benefits , if any, you could gain from a source based distribution like Gentoo.

The answer being that this is the wrong question…

In fact my guess would be that the fastest binaries would be generated by carefully benchmarking each bit of software to determine the best compile options and then distributing the compiled binaries…

..However, that gets us back to a \”normal\” binary distribution again (rpm/deb, etc), plus all the associated dependency hell that goes with it

In my opinion (gentoo on a dozen servers), the point of a source based distro is good control over dependencies and ability to stay as bleading edge or stable as you need to. So I can have one server running an antique glibc with a cutting edge mysql and another server running a cutting edge glibc with some old version of nginx (or whatever)

Additionally it\’s very easy to update a bunch of servers over long periods of time without suffering the downtime of a full \”upgrade\”. Show me a Centos system installed 4 years ago and yet still running bang up to date glibc/mysql/apache, etc.

Finally, given a build template to create SomeSoftware-V1, it\’s usually fairly trivial to bump the template to create SomeSoftware-V1.1 and hence usually source distros can help you stay up to date with bleeding edge more easily. Now someone will shout that this is inappropriate for servers, but even there sometimes you want to track some new and fast moving utility, eg my MySql servers are pinned to some known version, but I track bleeding edge Maatkit mysql tools (since they are in fast development mode right now)

More related to Gentoo, and less to source distro\’s in general, but gentoo makes it very easy to have machine \”profiles\” which mandate software versions, optional features (USE flags), compile options and even base packages which must/must not be installed. So for example I have a web server template which requires a modern gcc to be used, hardened compiler flags to be used, certain versions of nginx to be installed, again with various default modules that nginx should support. So in many ways something like Kickstart for Redhat… But the cool thing is I can update the template right now and then all my machines pull in the changes and rebuild whatever is required to get to the end result!

The penalty of source based distros is package generation time (essentially gentoo still needs a binary package, it just builds it on demand instead of it being pre-built). However, for my needs I mitigate this by keeping all my servers \”similar\” and then my package repository is automatically re-used after the first machine updates.

So my usual update procedure is to copy one of my virtual servers, test the upgrade in the copy, if all goes well then run the upgrades on the live server(s) (takes only seconds per package).

Gentoo is not likely suitable for the majority audience, but if you have strong admin skills then it\’s a great fit and will allow you to very easily run lots of servers with variable configs, all very easily

Gentoo provides a flexible framework for you to do whatever it is you want, yourself.

-c

No particular issues to note from upgrading…

On the other hand I have some CentOs box running my phone system and it drives me nuts that I remain pinned to antique versions of stuff I would like to upgrade, but I either need to ditch the centos packages and roll my own, or some other equally painful path

However, Gentoo likely does NOT suit the average punter who does not need that level of control. There is quite a significant complexity over head to get to grips with. So it comes down to the old adage of choosing the best tool for the job…

If I build an embedded system using a 486 class processor, I would want everything compiled for that processor. The same holds true that if I build a newer system, I would want everything compiled to take advantage of new specialized instructions.

Binary packages can only be compiled to take advantage of a common subset of features found on the oldest supported processor for a given build. Hence some distro\’s have separate builds for x86, I386, I686,…

Building from source does take time, but with the proper compile options selected, you can make better use of CPU features. The gains may be small, but they can help. Gentoo does offer the ability to install using binaries instead of source if desired.

It may be baptism by fire, but anyone who really wants to understand how everything works in Linux needs to build at least one system from scratch using a distro like Gentoo.

Most certainly makes a difference on 64bit code, not so sure on the effect on 32bit code.

It is also possible to specify per-package CFLAGS/CXXFLAGS which allows tuning of individual packages if there is anything that requires maximum performance, rather than just the generic system CFLAGS/CXXFLAGS.

I\’ve been a Gentoo\’st for around 6 to 7 years and have been best served by using the minimal flags, just \”-march=(arch) O2 -pipe\”.

However, USE flags are another matter. I think these make large differences in the system build, and while the USE flags in my make.conf are very few, I do have a very large packages.use file. Nearly a rule for every package on my system.

Regards, Rob

If you are going to do a lot of video/audio work, then I would be tempted to look at per=package optimisations for some of the video/audio codecs, indeed I am experimenting with hugin and it\’s dependencies, mainly just for the sake of curiosity, using some of the new graphite flags. BUT I wouldn\’t use them for the whole system.

USE flags are amazing, and indeed, the main reason for using gentoo. I think I probably took the opposite approach to yourself, as I have a large number, mainly video/audio/image flags in my /etc/make.conf, but I do have some overrides in /etc/portage/packages.use.

Rob.