[Yum-devel] Fastest mirror selection plugin

[Michael Stenner]

On Tue, Nov 29, 2005 at 12:22:24PM -0500, Matthew Miller wrote:
> On Tue, Nov 29, 2005 at 10:15:59AM -0700, Michael Stenner wrote:
> > > Would be nice, but how do you measure the time with url operations: I 
> > > guess you could grab 1 byte of "something" and time that, but what if the 
> > > server doesn't support byte ranges? Those would get penalized pretty 
> > > badly... but hey, maybe that's for a good reason ;)
> > Well, you could use urlopen, which opens a connection but doesn't
> > actually read anything.  The problem is that you still need to give a
> > file to ask for.  I think that's the same with any proxy operation,
> > though.  You'll need to ask for some file.
> 
> But would you be able to tell anything meaningful about the speed
> that way?

Actually, I think you would.  The local overhead associated with
urlgrabber is small and consistent, so it would even out.  The extra
time involved in establishing a data-bearing connection is actually
relevant information, so that's no problem, either.

> Maybe the easiest thing to do is just define the plugin as not working if
> there's a proxy, and automatically disable itself in that case. If your
> systems are going through a proxy, you 1) are already modifying the yum
> config (right?) and 2) you probably want to set the repo by hand so all
> systems are hitting the same one so you can cache efficiently.

That's pretty reasonable, too.  Honestly, I think the whole concept
lives on the edge of kludge, so finding elegant solutions is gonna be
hard right from the outset.  I'm happy to see graceful failure along
the lines of "hey somethings weird... lets just do things the
old-fashioned way".
					-Michael
-- 
  Michael D. Stenner                            mstenner at ece.arizona.edu
  ECE Department and Optical Sciences Center                520-626-1619
  University of Arizona                                         ECE 524G