Date: Fri, 25 Mar 2016 20:55:54 +0000 (UTC) From: "Bjoern A. Zeeb" <bz@FreeBSD.org> To: Gleb Smirnoff <glebius@FreeBSD.org> Cc: "George V. Neville-Neil" <gnn@FreeBSD.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r297225 - in head/sys: net netinet netinet6 Message-ID: <alpine.BSF.2.00.1603252049180.92377@ai.fobar.qr> In-Reply-To: <20160324203117.GY2616@FreeBSD.org> References: <201603240754.u2O7suvM006925@repo.freebsd.org> <20160324203117.GY2616@FreeBSD.org>
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On Thu, 24 Mar 2016, Gleb Smirnoff wrote: > On Thu, Mar 24, 2016 at 07:54:56AM +0000, George V. Neville-Neil wrote: > G> Author: gnn > G> Date: Thu Mar 24 07:54:56 2016 > G> New Revision: 297225 > G> URL: https://svnweb.freebsd.org/changeset/base/297225 > G> > G> Log: > G> FreeBSD previously provided route caching for TCP (and UDP). Re-add > G> route caching for TCP, with some improvements. In particular, invalidate > G> the route cache if a new route is added, which might be a better match. > G> The cache is automatically invalidated if the old route is deleted. > G> > G> Submitted by: Mike Karels > G> Reviewed by: gnn > G> Differential Revision: https://reviews.freebsd.org/D4306 > > I'm quite surprised to see this checked in, taking into account that the > D4306 has strong disagreement from melifaro@. > > So, now we got two aids for poor routing: TCP route caching & flowtable. I am uncertain by what you mean when you say "routing". For as forwarding is concerned, this doesn't matter. For as local connections are concerned, this is the start to scale again. You are saving 1-2 route lookups per first packet and 2-3 route lookups for any subsequent packet. Worst case scenario your FIB changes for each packet still improves the situation as in the first packet situation. Every lookup I don't have to do I don't have optimize a system for as badly as I would otherwise have to. Flowtable in my view, once this is fully flashed out, has no real reason to be used anymore. Everything else I think my initial reply and gnn's reply has covered. /bz
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