[Server-devel] Squid tuning recommendations for OLPC School Server tuning...

[Mark Nottingham]

On 23/09/2008, at 2:40 PM, Martin Langhoff wrote:

> On Tue, Sep 23, 2008 at 4:12 PM, Mark Nottingham <mnot at yahoo- 
> inc.com> wrote:
>> Overall, what do you want to use Squid for here; caching, access  
>> control..?
>
> Caching and plugins such as squidgard (does that qualify as access  
> control?)
>
>> If you want caching, realise that you're not going to see much  
>> benefit from
>> such a resource-limited box, and indeed it may be more of a  
>> bottleneck than
>> is worthwhile.
>
> well, we are very constrained RAM wise, but we have a reasonable hard
> drive quota *and* a horrible internet connection. Picture 200 kids
> behind a dsl line, 50 kids behind a satellite link or 3G modem.

Hmm, way back when I administered a Squid with about 200 investment  
bankers behind an ISDN line... sounds familiar :)

The main problem is going to be the RAM; having it for cache removes a  
lot of the pressure on your disk, and most ISP caches with this kind  
of workload get IO bound. The per-connection overhead isn't trivial,  
either, when you've got a slow link, as users will tend to be  
impatient and retry, surf with multiple windows, etc.

BTW, completely out of left field, have you seen this?
   http://www.eecis.udel.edu/~nataraja/papers/nsdr2008.pdf

There is a group of folks talking about adding SCTP support to squid  
(there are already patches for apache and firefox); with that, you  
could use SCTP over the lossy/low bandwidth hops to improve  
performance. I think in your case it would require a server on the  
other end of the link -- e.g., maybe a farm of HTTP/SCTP -> HTTP/TCP  
gateways -- but it may be worth considering...

Cheers,


>
>
> Granted, youtube isn't going to work but well-behaved cacheable
> content (in http terms) can work well with a good proxy.
>
> cheers,
>
>
>
> martin
> -- 
> martin.langhoff at gmail.com
> martin at laptop.org -- School Server Architect
> - ask interesting questions
> - don't get distracted with shiny stuff - working code first
> - http://wiki.laptop.org/go/User:Martinlanghoff

--
Mark Nottingham       mnot at yahoo-inc.com