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The C10M problem

c10m.robertgraham.com

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Re: The C10M problem

#51

Post by nl »

dbenhur wrote: post #43
electrograv wrote: post #25

Earlier quoted context omitted.

It really just depends on how much of a computational surplus you have. Some tasks have become so incredibly easy relative to today's computational horsepower, that we can afford waste 90% of it if it means we can be 10% more productive. But this isn't true everywhere. Imagine if Google's servers cost 100x more to run, if they didn't spend time to make their code efficient. Imagine if your video games ran at a frame…

> when languages like Python and Ruby can be over 100x slower than other high level languages You said a wrong thing. Java is a far cry from a high-level language. Javascript is arguably a high-level language however, and meaningless benchmarks (aka "damn lies") attest V8 is in spitting distance of Java. http://benchmarksgame.alioth.debian.org/u32/javascript.php Scala is much higher level than Java, compiles to the s…

"languages like Python and Ruby can be over 100x slower than other high level languages"

Notice the "can be"? It's important.

And I don't think arguing if Java is a high level language or not is very useful in this context. Notice that C++ was also included as a "high level" language. Clearly if C++ is high level then Java is too.

Anyway, the point of that comment wasn't which languages are high level - it's that efficiency is important, because some languages have areas where performance suffers.

Clearly that is true (at least to some extent) as the use of Numpy in Python shows.

I'd argue that writing Numpy (and other high-performance libraries for use in high level languages) isn't "general purpose programming" (which is what the OP) was talking about, but that is also a different discussion.

Re: The C10M problem

#52

Post by nl »

erichocean wrote: post #16

What's significant to me is that you can do this stuff today on stock Linux. No need to run weird single-purpose kernels, strange hypervisors, etc. You can SSH into your box. You can debug with gdb. Valgrind. Everything is normal...except the performance, which is just insane. Given how easy it is, there isn't really a good excuse anymore to not write data plane applications the "right" way, instead of jamming everyt…

Snabb Switch looks awesome.

Is there a list of "things" (not sure of the terminology?) people have built with it?

I guess the downside is that you can't virtualize it (I realize that is kind of the point, but it does reduce the accessibility of it).

Re: The C10M problem

#53

Post by sp332 »

perlgeek wrote: post #40
dxhdr wrote: post #20

Earlier quoted context omitted.

Port numbers must only be unique for ip:port pairs. A TCP connection is identified by the "quadruple" source_ip:source_port, dest_ip:dest_port. You can have as many connections as you want on the same source_ip on port 80 as long as there aren't 65,535 to the same dest_ip (ie as long as the quadruple is unique).

Also with IPv6 you can easily route a whole /64 net (2 64 IPs!) onto a single machine.

2^64 IPs. :)

Re: The C10M problem

#54

Post by [deleted] »

perlgeek wrote: post #40
dxhdr wrote: post #20

Earlier quoted context omitted.

Port numbers must only be unique for ip:port pairs. A TCP connection is identified by the "quadruple" source_ip:source_port, dest_ip:dest_port. You can have as many connections as you want on the same source_ip on port 80 as long as there aren't 65,535 to the same dest_ip (ie as long as the quadruple is unique).

Also with IPv6 you can easily route a whole /64 net (2 64 IPs!) onto a single machine.

[deleted]

Re: The C10M problem

#55

Post by joosters »

If you are going to write a big article on a 'problem', then it would be a good idea to spend some time explaining the problem, perhaps with some scenarios (real world or otherwise) to solve. Instead, this article just leaps ahead with a blind-faith 'we must do this!' attitude.

That's great if you are just toying with this sort of thing for fun, but perhaps worthless if you are advocating a style of server design for others.

Also, the decade-ago 10k problem could draw some interesting parallels. First of all, are machines today 1000 times faster? If they are, then even if you hit the 10M magic number, you will still only be able to do the same amount of work per-connection that you could have done 10 years ago. I am guessing that many internet services are much more complicated than a decade ago...

And if you can achieve 10M connections per server, you really should be asking yourself whether you actually want to. Why not split it down to 1M each over 10 servers? No need for insane high-end machines, and the failover when a single machine dies is much less painful. You'll likely get a much improved latency per-connection as well.

Re: The C10M problem

#56

Post by dagw »

logicchains wrote: post #36
usea wrote: post #34

Earlier quoted context omitted.

It is wasteful to spend time doing something that benefits nobody, or where the benefits outweigh the cost. Your time is worth something.

The point I was trying to make is that if you spend your time to make something that works really efficiently, and you take pride in it, then you haven't wasted your time. It doesn't benefit nobody, it benefits yourself, because you can take pride in your work. At least, I believe this idea is part of what's implied in the traditional notion of 'craftsmanship'. An example might be working nine hours per day rather th…

Except the difference at the margin is never just an extra hour of a day. It's almost always weeks instead of days or years instead of month. And that is fine when you are doing things for yourself and have no other requirements on your time, but when you're being paid spending two month on something instead of week just pisses everybody around you off.

I mean don't get me wrong, I'm working on a project right now that I'd love to do 'right'. Spend weeks doing a literature study to catch up on and really understand the current state of the art, then implement three or four different approaches to really get a feel how they work under real world conditions. After that I would try to pick the best aspects of those algorithms and try to write some really smart code that analyses the input and picks the best algorithm based on the data. Then I would tune that code until it is as fast, stable and memory efficient as possible and finally put a really slick UI on top of it. Trust me, nothing would give me greater satisfaction.

Unfortunately I got the project late last week, deadline is in less than two weeks and I have two other projects I'm working on in parallel. So I'm going to end up grabbing some off the shelf solution, tweaking it until it works well enough, wrapping it in up in some hacky shell script and make up for inefficiency by throwing more hardware at the problem. It's not optimal, but deadlines are deadlines, and I'll have a contend myself with the satisfaction of getting a job done well enough on time, rather than a job done perfectly.

Re: The C10M problem

#57

Post by logicchains »

dagw wrote: post #56
logicchains wrote: post #36

Earlier quoted context omitted.

The point I was trying to make is that if you spend your time to make something that works really efficiently, and you take pride in it, then you haven't wasted your time. It doesn't benefit nobody, it benefits yourself, because you can take pride in your work. At least, I believe this idea is part of what's implied in the traditional notion of 'craftsmanship'. An example might be working nine hours per day rather th…

Except the difference at the margin is never just an extra hour of a day. It's almost always weeks instead of days or years instead of month. And that is fine when you are doing things for yourself and have no other requirements on your time, but when you're being paid spending two month on something instead of week just pisses everybody around you off. I mean don't get me wrong, I'm working on a project right now th…

> Except the difference at the margin is never just an extra hour of a day. It's almost ways weeks instead of days or years instead of month.

Maybe we're thinking of different things here. What I had in mind was more along the lines of for instance choosing Go or Scala instead of Rails or *.js and getting a 10x speedup at the cost of simply adding a few type declarations. There are situations like yours where deadlines leave little choice, but there are also situations where a bit more leeway is available.

Re: The C10M problem

#58

Post by slashnull »

The two bottom-most articles (protocol parsing and commodity x86) are seriously pure dump, but fortunately the ones about multi-core scaling are pretty damn interesting.

Re: The C10M problem

#59

Post by sitkack »

srean wrote: post #42
usea wrote: post #34

Earlier quoted context omitted.

It is wasteful to spend time doing something that benefits nobody, or where the benefits outweigh the cost. Your time is worth something.

I think the "just good enough for business" attitude contributed to the demise of the American car and the rise of the Japanese ones. The American tradition was to use engineering tolerances that would maximize throughput under the constraint that it produced a pretty functional car. The Japanese tradition on the other hand was to use tighter tolerances, well because there was room for tightening the tolerance. At th…

Your recollection of Japanese manufacturing is clouded by mythology. Japanese quality sucked in the 1950s, they had a horrible world wide reputation for shoddy goods.

Re: The C10M problem

#60

Post by stock_toaster »

erichocean wrote: post #16

What's significant to me is that you can do this stuff today on stock Linux. No need to run weird single-purpose kernels, strange hypervisors, etc. You can SSH into your box. You can debug with gdb. Valgrind. Everything is normal...except the performance, which is just insane. Given how easy it is, there isn't really a good excuse anymore to not write data plane applications the "right" way, instead of jamming everyt…

Userspace network stacks (like this[1]) on top of things like netmap[2] are also very cool.

  [1]: http://conferences.sigcomm.org/hotnets/2013/papers/hotnets-final43.pdf
  [2]: http://info.iet.unipi.it/~luigi/netmap/
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