Facebook Is Hiring To Make Linux Networking Better Than FreeBSD

[david_lynch]

The large corporations and businesses that have servers. If I remember correctly, Netflix has FreeBSD servers. Right there you have about 10-20% of internet traffic.

While netflix apparently does have some FreeBSD servers, it is well known that they have a major investment in Linux infrastructure.

[jimbohale]

The statements that "Linux is the fastest" and "We want to make it faster" are not mutually exclusive

If it's fast and the CPU load is still high then there's a problem. That's where I suspect they are targeting. For me, my NAS bottlenecks on Linux and not FreeBSD due to CPU usage because it *is* low-spec'd, but it's not like it's that low. It's just an atom processor, and I'm quite certain atom's are useful in servers due to their low power consumption. I get straight gigabit transfer speeds with FreeBSD with relatively low CPU load, 50 MB/s at the most (on any service) on Linux and CPU load at 100%.

[david_lynch]

If it's fast and the CPU load is still high then there's a problem. That's where I suspect they are targeting. For me, my NAS bottlenecks on Linux and not FreeBSD due to CPU usage because it *is* low-spec'd, but it's not like it's that low. It's just an atom processor, and I'm quite certain atom's are useful in servers due to their low power consumption. I get straight gigabit transfer speeds with FreeBSD with relatively low CPU load, 50 MB/s at the most (on any service) on Linux and CPU load at 100%.

To be sure, there are further opportunities for optimization in the Linux kernel. BSD has been doing things right for many years.

[jimbohale]

To be sure, there are further opportunities for optimization in the Linux kernel. BSD has been doing things right for many years.

Which is why I like how it's being done. Rather than them saying 'Linux sucks, use FreeBSD', they are saying 'We are looking to pay someone to increase Linux to the benchmark of being as good as FreeBSD'.

[nasyt]

Keep dreaming. Linux beat it years ago. That's why companies migrate their servers to Linux and that's why Linux server market share is MUCH higher than BSD:

http://en.wikipedia.org/wiki/Usage_s...n_the_Internet

And thats, why companies generally have trouble with their networking.

Linux has basically a bad network stack.

http://www.softpanorama.org/Articles/Linux_vs_Solaris/comparison_of_internal_architecture.shtml#Networking

Linux networking was significantly improved after famous Mindcraft fiasco . The latter took place in the early 1999 and was related tot he results of Microsoft sponsored (and Mindcraft executed) tests that showed that despite Raymondism claims, Linux 2.2 had problems in the application area were it is most widely used -- as a web server. Windows NT simply wiped the floor with Linux. Here are some important results from the test (which was devastating to the pride of linuxoids, and served as an important stimulus for the improvement of the subsystem):

With 4 CPUs and 1 Gig of RAM, NT & IIS achieved 4,166 http requests per second.
With 4 CPUs and 1 Gig of RAM, Linux & Apache achieved 1,842 http requests per second.
With 1 CPU and 256 MB RAM, NT & IIS achieved 1,863 http requests per second.
With 1 CPU and 256 MB RAM, Linux & Apache achieved 1,314 http requests per second.

http://www.kegel.com/mindcraft_redux.html

this site shows the issues.

Kernel issue #1: TCP bug

I assume this was just the tip of the iceberg

Gets hired to improve the Linux network stack, ends up migrating all servers from Linux to others.

[Michael_S]

And thats, why companies generally have trouble with their networking.

Linux has basically a bad network stack.

http://www.softpanorama.org/Articles/Linux_vs_Solaris/comparison_of_internal_architecture.shtml#Networking

http://www.kegel.com/mindcraft_redux.html

this site shows the issues.

That site has some article links on the top as recent as 2003 but the actual items discussed on the page are from 2000 and the author is careful to point out that the benchmarks in which NT + IIS beat Linux 2.4 + Apache 1.3 were conducted at a Microsoft lab with access to Microsoft's NT tuning resources versus an off-the-shelf Linux install with no support assistance from any enterprise Linux vendor or support contractor and it measured speed for delivering static pages and not dynamically generated pages which are dramatically more common in high volume web applications.

Since 2000, the Linux kernel support for SMP has gotten better. The TCP stack has been improved. The scheduler has been improved. The ethernet card drivers have been improved. This is not the 2.4 kernel any more.

Apache has also improved - but if you're going to serve static content, today it might make more sense to benchmark against nginx.

I assume this was just the tip of the iceberg

Gets hired to improve the Linux network stack, ends up migrating all servers from Linux to others.

Fourteen years ago. I don't see any evidence the same would happen today.

[Michael_S]

(Follow up)

To be fair, I've read interviews with Windows developer Mark Russinovich in which, in the late 1990s, he criticized the Linux kernel for lacking some forms of asynchronous IO, for only offering 'select' for waiting for events, for only having partial support for reentrant calls, and at the time the NT implementation of sendfile worked better with the filesystem cache than the Linux implementation of sendfile. (See: http://windowsitpro.com/systems-mana...se-01-apr-1999 )

I strongly suspect that at that time, there were a lot of Linux zealots who ignored his points and ignored other people who made similar points. But as far as I know, the current Linux kernel has addressed every one of those issues.

[curaga]

Linus has said in interviews how that NT test was considered a bug report, and promptly resulted in improved web server performance on Linux.

[Karan Upadhaya]

Probably because in other respects, Linux fits the needs of Facebook better. Not being Facebook, I cannot say why. Linux has wider hardware support, but that probably is a non-issue for a company that buys servers by the boatload, and therefore could specify devices that work well with FreeBSD. Perhaps their software has developed dependencies on the details of Linux.