OT: limit number of connections from browser to my server?

[Grant Edwards]

On 2016-05-17, Rob Gaddi <rgaddi at highlandtechnology.invalid> wrote:
>
>> How can you not serve a web page over your LAN in 15s?
>>
>> I mean, you could *almost* do it by hand, copying the files onto a
>> USB stick and walking them across the room in 15 seconds. Maybe 30.
>
> Simple, because embedded web servers running on toy microprocessors are
> HARD.

40MHz with multiple MB of RAM is pretty high-end in my book.  I've
worked on projects where the clock speed was in KHz, the supply
current was measrued in micro-Amps, and there were a few KB of RAM.
Of course you don't try to do TCP and SSL on something like that.

> When you're trying to work with whatever browser the customer may
> have, you have no control over the number of simultaneous connections 
> it will try to make to your box.  If you don't allow those connections
> it can cause huge stalls by forcing the TCP layer to time out.  If you
> do, in Grant's case, it forces you to perform tons of expensive
> public-key crypto on a 40 MHz processor (which, hmmm, external memory
> bus, ~40 MHz... Coldfire?).

The 40MHz one is a Samsung ARM7TDMI.  There's a newer model with a
133MHz Cortex-M3.  For most things it's 2-3 times faster than the
ARM7, but the ARM7 has an I/D cache and the M3 doesn't.  So there are
few highly localized tasks where there's not a lot of difference.

> A lot of things you can take for granted on a compute monster (like
> a Chromebook or Atom based laptop) get much more complicated when
> you're resource constrained.

And that's what keeps me paid. :)

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Grant Edwards               grant.b.edwards        Yow! I know th'MAMBO!!
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