From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-x22c.google.com (mail-oi0-x22c.google.com [IPv6:2607:f8b0:4003:c06::22c]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 2F6383B29E for ; Sun, 26 Aug 2018 20:55:32 -0400 (EDT) Received: by mail-oi0-x22c.google.com with SMTP id k12-v6so24430654oiw.8 for ; Sun, 26 Aug 2018 17:55:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=a9UmVAqClRaWg7rGQXBOzhXs+Ymh84VxTwhRP0DU4hE=; b=i7yjxmdo2nSI/eUqWBcrCVUIDtHoTF2N2+WNIXJGfQNoox9M40IMEf0qaPF92UxcV4 cdRCBSOisN+T/k2Wga8jsxyotkkuNDQCAVF6G8JqEx8enHZXuTFq1t6oBagGTdg8DPc+ g0SVEM5rf7uPbejwH/y4iaYvzIYRQ1w87VsAn/qF6zeAAKvmTdtWyL+h2brNTK5sbvPD 5aYEnyYWXZ7D0NdeBKdrukZV7lVKjRN+NH+mPfkwkc4o6ueunw/kjqwsPNTLJDbaFmLT fyd6mS7gOZhGtaXHUf39Y6arcMRIysRaC3kH+o9LPUrIyBLOSEIAHYoS1lwTJYwKwYTh Otag== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=a9UmVAqClRaWg7rGQXBOzhXs+Ymh84VxTwhRP0DU4hE=; b=LWZLlrXcotbsI84EKCiuruzUuOS5tpnPWzWFjbc3Z+gyAS3aHXLOfIiLqtechP/PIl QK/UIANRt/odYHymclK4GMZXY1i5aTIVxbGzunS308+EkjQRgrY1Mfh8B8A4SgR8SiXX 9+AL3PEqy06JMKrbelBQ/HOtZ5f5j4x8/Io1ncrG6mlFGTYn3RdRTUOtXqVlE0QLZgZk NkaNdA2DvW3smnz3TVRQhAhBboT0K6vJfcehXadtgiJqOrFkWIDWaOX3eQJghYtdcx3B x6EfubiSWfrnPpHH+hpNyCRg7NZVM9LS0gikxHA3QqVcq+1Wiwezc8SekfZvRRO61+zM Wezg== X-Gm-Message-State: APzg51Cz1g0gkBuY9GqKoTT3tDHXnfAuW9qQQERdcLw73jwllXmYdsdy U4wP9sfvFPcjYk7RSHCs6r1IezUuvmorgygJuq4= X-Google-Smtp-Source: ANB0VdbX+CxkDDwnC5zv8NlfuJIR5Wi1RFhKU+mx6S7eneBnjrPCezBQmImOR0iGyW8IRJ+W7cuHHb83eh3zgrcQ5qY= X-Received: by 2002:aca:e510:: with SMTP id c16-v6mr11201824oih.44.1535331330233; Sun, 26 Aug 2018 17:55:30 -0700 (PDT) MIME-Version: 1.0 References: <66e2374b-f998-b132-410e-46c9089bb06b@gmail.com> <360212B1-8411-4ED0-877A-92E59070F518@gmx.de> In-Reply-To: From: Rosen Penev Date: Sun, 26 Aug 2018 17:55:22 -0700 Message-ID: To: Dave Taht Cc: Mikael Abrahamsson , bloat Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: Re: [Bloat] Marvell 385 X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 27 Aug 2018 00:55:32 -0000 On Sun, Aug 26, 2018 at 2:09 PM Dave Taht wrote: > > On Sun, Aug 26, 2018 at 1:58 PM Rosen Penev wrote: > > > > On Sun, Aug 26, 2018 at 11:44 AM Mikael Abrahamsson = wrote: > > > > > > On Sat, 25 Aug 2018, Dave Taht wrote: > > > > > > > The expressobin is a Marvell Armada "3700LP (88F3720) dual core ARM > > > > Cortex A53 processor up to 1.2GHz" - how does that compare? I have > > > > plenty of ath10k and ath9k pcmcia cards.... > > > > > > I have one of these, incl wifi. Right now the drivers are not in grea= t > > > shape, but they're being worked on. My espressobin has worse performa= nce > > > than on its wired ports than my WRT1200AC (Armada 385). > > If as you mentioned earlier that ethernet performance is limited by > > interrupts, then this commit is kind of depressing: > > > > https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/com= mit/drivers/net/ethernet/marvell/mvneta.c?h=3Dnext-20180824&id=3D0f5c6c30a0= f8c629b92ecdaef61b315c43fde10a > > I was on that thread. It was broken before entirely. As for the single > interrupt on this chip variant - believe it or not, I'm not huge on > lots of different interrupts for everything. I'd like it if we had > more than an rx or tx interrupt > in general, I'd love it if we had a programmable "tx is almost done" > interrupt that you could tune to the > interrupt latency... and it's complicated and costs wires to have lots > of different interrupt types... and (fantasizing again) I'd love it if > we had a scratchpad or dedicated memory to store interrupt handlers in > rather than relying on cache.... > > I'd looked deeply into improving this driver once upon a time, and > wanted to rip the software gro out of it, > in particular, and not defer things as much, trying things like NAPI > of 16 and measuring where time was spent. The copy to memory is > expensive, and then it defers further work. > > Less code, particularly near interrupt time, is better than a lot. > adding XMIT_MORE to the ar71xx driver (which hurt it badly) is one > example. I've been looking a lot at ag71xx. The driver has so much low hanging fruit. Unfortunately I lack the knowledge to fix most of it. This patch for example gives me a ~20-30mbps improvement in iperf tests: https://pastebin.com/ZExWjXQZ It's kind of unfortunate given how much atheros hardware is out there. > > Given something *cool* now landing ( skb list batching, see lwn ) it > would be worthwhile to revisit this. I don't care if I get more > interrupts/sec (particularly on a multicore) if we could drain the rx > ring over smaller intervals... > > but that's me, I'm all about the latency. :) Nobody's willing to rip > the latency out of stuff, they'd rather add features. It's really hard > to correctly measure interrupt latency regardless. > > > > > > > > I have talked to people who say the drivers are being worked on thoug= h... > > > If you have input, Kaloz is probably a great person to take that inpu= t. I > > > know other people working on Marvell drivers as well. > > > > > > -- > > > Mikael Abrahamsson email: swmike@swm.pp.se > > > _______________________________________________ > > > Bloat mailing list > > > Bloat@lists.bufferbloat.net > > > https://lists.bufferbloat.net/listinfo/bloat > > > > -- > > Dave T=C3=A4ht > CEO, TekLibre, LLC > http://www.teklibre.com > Tel: 1-669-226-2619