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Re: where is setup.exe source?
On Sun, 6 Nov 2005, Brian Dessent wrote:
> Igor Pechtchanski wrote:
> > I disagree. FWIW, keeping the local ping response time information for
> > mirrors and re-pinging on demand has been on my TODO list for a while.
> > The only thing I would strenuously object to is re-pinging the mirrors
> > automatically on every setup -- it's much better to let the user update
> > the mirror information (by adding a "Ping" button). I don't recall if the
> > mirror list is sortable, actually -- if it isn't, it ought to be. BTW,
> > now that setup is resizable, it would make sense to at least add the
> > location information from mirrors.lst to the mirror list dialog.
> Well there's fundamentally two different concepts going on here.
> A) Is the mirror online and fresh? This is taken care of by the
> infrastructure at cygwin.com.
> B) Based on *my* connection, is the mirror fast? This obviously is
> something that can only be measured by the end user. However, ping is a
> really poor way to judge bandwidth. One of the main reasons is that
> carrier grade routers do standard IP packet forwarding in hardware line
> cards (at full line rate) but they often punt things like ICMP and SNMP
> to be handled by the CPU which is much slower. More at
> <http://www.iwl.com/Resources/Papers/icmp-echo_print.html>. So a low
> ping doesn't correlate to high bandwidth, and vice versa.
Heh. I should've quoted the "ping"... What I meant by "ping" above is
some measure of the connection speed, not the actual ICMP packets.
Besides, doing ping in software requires an ICMP-compliant library.
> [snip more "ping" vs "connection speed" discussion]
> I would argue the only way to measure this is by manually experimenting
> with various mirrors and finding one from which you can download fast.
> This too could be automated by setup, but it is a lot harder than just
> measuring pings. And you would want to do it in a way that doesn't
> cause abuse, i.e. you wouldn't want to always download a 1MB file from
> every mirror just to see which one is the fastest.
Yes, fully agreed. That's why I'm waiting for a really large round tuit,
rather than doing something quick and dirty, but braindead. However, the
"always" in your statement above isn't that bad, since it won't happen
unless a user chooses to perform that action. I also vaguely recall
reading something about a standard bandwidth-test download that won't be
considered "abuse" (it probably would be much smaller than 1MB). If
anyone recognizes what I'm talking about, I would appreciate a pointer in
> Also, personally, I tend to find one mirror that I like and stick with
> it. All the mirrors on the official list have the same set of packages
> so once you find a suitable mirror it makes no sense to then try others,
> unless you experience connection problems. So I don't really see a need
> for adding a lot of automation to measuring bandwidth.
Picking that first mirror can be a hassle, too. But even if you have a
mirror, it's nice to know what other options are available. There is also
a question of server load... Not everyone uses setup in the same way.
> > Yuk. Then you'd need to pass this information to setup (not easy, as
> > setup actually grabs one from cygwin.com). It's better to do this in
> > setup proper.
> Well again, I see it defined more as "I want to measure this once and
> find a suitable mirror, which I then select in setup" as opposed to "I
> will need ongoing measurements and rankings because I will be constantly
> selecting the best mirror." From that perspective, you can write a
> simple perl script that downloads a package from each mirror in the list
> and tells you which one is the fastest - there's no need to communicate
> this back to setup.exe since you can just pick that mirror and be done
> with it.
Well, yes, if you put it that way. However, there's a chicken-and-egg
problem here, right? As in "I want to download Cygwin fast" needs Cygwin
to figure it out[*]?
[*] And I'm not even going to suggest using a non-Cygwin set of tools to
write that script...
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