Date: Thu, 23 Jan 2020 17:24:58 -0800 From: Gleb Smirnoff <glebius@freebsd.org> To: Ryan Stone <rysto32@gmail.com> Cc: src-committers <src-committers@freebsd.org>, svn-src-all <svn-src-all@freebsd.org>, svn-src-head <svn-src-head@freebsd.org> Subject: Re: svn commit: r357051 - head/sys/dev/bge Message-ID: <20200124012458.GI1268@FreeBSD.org> In-Reply-To: <CAFMmRNwhcV-%2BSsq_a1RZJYXC8wvnUDLDxdFeHD7PgL5wuierkg@mail.gmail.com> References: <202001231636.00NGawrr080128@repo.freebsd.org> <CAFMmRNyP5nKPZ62c9yRktH4t23GAgnpc2u8kHhUevUCu3doAQQ@mail.gmail.com> <20200123230546.GG1268@FreeBSD.org> <CAFMmRNwhcV-%2BSsq_a1RZJYXC8wvnUDLDxdFeHD7PgL5wuierkg@mail.gmail.com>
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On Thu, Jan 23, 2020 at 08:17:46PM -0500, Ryan Stone wrote: R> On Thu, Jan 23, 2020 at 6:05 PM Gleb Smirnoff <glebius@freebsd.org> wrote: R> > R> > On Thu, Jan 23, 2020 at 02:17:33PM -0500, Ryan Stone wrote: R> > R> What is a driver's responsibility now for entering/leaving the net epoch now? R> > R> > For drivers that are 'special', entering the net epoch is necessary. Special R> > usually means running if_input outside network interrupt context. R> > R> > However, there is plan to generalize entering/exiting epoch for taskqueues R> > and callouts. R> R> Why on earth is it done that way rather than putting the network epoch R> enter/exit in ether_input? I'm with Ian; this sounds like a huge R> layering violation. Because at interrupt level we can batch multiple packets in a single epoch. This speeds up unfiltered packet forwarding performance by 5%. With driver level pfil hooks I would claim even more improvement, because before the change we needed to enter epoch twice - once for filtering, than for ether_input. Epoch isn't a layer, it is a synchronisation primitive, so I disagree about statement on layering violation. -- Gleb Smirnoff
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