Messages in this thread |  | | | Subject | Re: [PATCH] tcp: Implement a two-level initial RTO as per draft RFC 2988bis-02. | | From | Alexander Zimmermann <> | | Date | Thu, 19 May 2011 08:36:09 +0200 |
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Am 19.05.2011 um 08:25 schrieb tsuna:
> On Wed, May 18, 2011 at 11:10 PM, Alexander Zimmermann > <alexander.zimmermann@comsys.rwth-aachen.de> wrote: >> Am 19.05.2011 um 06:33 schrieb tsuna: >>> Presumably if the user decides to tweak these knobs, they'll know >>> what's appropriate for their environment. >> >> Are you sure? I'm not. I fully agree with David that minRTO is > > s/minRTO/initRTO/, right?
Yes of course :-)
> >> something that a user shout not control at all > > I personally don't like to hold the hand and spoon feed users too > much, I want to trust them to be responsible and know what they're > doing. Yes, there will always be people who will act stupid and do > stupid things with whatever knobs you expose. The web is full of > people who advise to tune up all the TCP rmem/wmem parameters to crazy > high level based on the voodoo belief that they're going to improve > their TCP performance, but then as long as you have knobs in your > system, these people will misuse them anyway and shoot themselves in > the foot, what can we do about that.
But if you tune rmen/wmen to crazy level, it's only your TCP performance that hurts (and maybe the receiver's one).
If you set the initRTO=0.1s, it's good for me but bad for the rest of the world. That's the difference.
Or do you want to implement a lower barrier of 1sec so that you can ensure that nobody set the initRTO lower than 1s?
> > There's also a good chunk of people who know what they're doing, and > for them compile-time constants are annoying because it's inconvenient > to experiment and iterate quickly when you need to recompile your > kernel to change a value. If turning the compile time constant into a > knob leaves the code reasonably straightforward and doesn't incur too > much overhead, then why not do it? > > Regarding this knob in particular, I can imagine that people who are > in environment where RTT easily gets around 1s will be upset by the > change in the default value, and doubly upset that they have to > recompile their kernel to change the value back to 3s. I'm in favor > of the reduction of initRTO, for the same reason Google is, but I can > also understand that the direction we're taking might not be > appropriate for everyone. > > -- > Benoit "tsuna" Sigoure > Software Engineer @ www.StumbleUpon.com
// // Dipl.-Inform. Alexander Zimmermann // Department of Computer Science, Informatik 4 // RWTH Aachen University // Ahornstr. 55, 52056 Aachen, Germany // phone: (49-241) 80-21422, fax: (49-241) 80-22222 // email: zimmermann@cs.rwth-aachen.de // web: http://www.umic-mesh.net // [unhandled content-type:application/pgp-signature]
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