Re: [PATCH] tcp: Expose the initial RTO via a new sysctl.

From: Eric Dumazet
Date: Tue May 17 2011 - 08:20:34 EST

Le mardi 17 mai 2011 Ã 13:02 +0200, Hagen Paul Pfeifer a Ãcrit :
> On Tue, 17 May 2011 10:07:57 +0200, Eric Dumazet wrote:
> > I wont discuss if introducing a new sysctl is welcomed, only on patch
> > issues. I believe some work in IETF is done to reduce the 3sec value to
> > 1sec anyway.
> Why not?

Just because I let this point to David and others. I personally dont
care that much.

> I though all new knobs in this area should be done on a per route
> metric so it can be controlled on a per path basis. RTO should be
> adjustable on a per path basis, because it depends on the path.

Adding many knobs to each clone had a huge cost on previous kernels.
(Think some machines have millions entries in IP route cache), this used
quite a lot of memory.

With latest David work, we'll consume less ram, because we can now share
settings, instead of copying them on each dst entry.

> Some months back [1] I posted a patch to enable/disable TCP quick ack
> mode, which has nothing to do with network paths, just with a local server
> policy. But David rejected the patch with the argument that I should use a
> per path knob (this is a little bit inapprehensible for me, but David has
> the last word).

Well, if nobody speaks after David, he has the last word indeed.

BTW, I remember Stephen actually asked the per route thing, not David.

Then David also stated it :

If you really want tcp_quickack thing you really should do it as
requested by both Stephen & David ;)

Unfortunately, I dont know if its really needed or worthwhile.

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