Return-Path: linux-nfs-owner@vger.kernel.org Received: from cantor2.suse.de ([195.135.220.15]:37734 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755419Ab3GPBLG (ORCPT ); Mon, 15 Jul 2013 21:11:06 -0400 Date: Tue, 16 Jul 2013 11:10:55 +1000 From: NeilBrown To: Jim Rees Cc: "J.Bruce Fields" , Olga Kornievskaia , NFS Subject: Re: Is tcp autotuning really what NFS wants? Message-ID: <20130716111055.566352aa@notabene.brown> In-Reply-To: <20130715134211.GA14237@umich.edu> References: <20130710092255.0240a36d@notabene.brown> <20130710022735.GI8281@fieldses.org> <20130715134211.GA14237@umich.edu> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/1V3/WbYw=2yjZZRAz0HW=4H"; protocol="application/pgp-signature" Sender: linux-nfs-owner@vger.kernel.org List-ID: --Sig_/1V3/WbYw=2yjZZRAz0HW=4H Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Mon, 15 Jul 2013 09:42:11 -0400 Jim Rees wrote: > Here's the thread on netdev where we discussed this issue: > http://marc.info/?l=3Dlinux-netdev&m=3D121545498313619&w=3D2 >=20 > Here is where I asked about an api to set a socket buf minimum: > http://marc.info/?l=3Dlinux-netdev&m=3D121554794432038&w=3D2 >=20 > There are many subtleties, and I suggest anyone who wants to try to fix t= his > code should read the email thread. The netdev people were pretty insistent > that we turn on autotuning; David Miller said the old behavior was > equivalent to "turn[ing] off half of the TCP stack." Thanks for those pointers. Certainly autotuning is what we want. The issues with the receive buffer getting tuned too low appear to have been addressed some time ago. The issues with the send buffer getting tuned too low are not what I at fir= st thought they were, but still are not completely resolved. My previous patch which allowed N requests beyond the available space is, I now think, more than necessary. You just need to make sure one can get though. That should be enough to push the sndbuf size up quite quickly. I'll revise it, test, and repost. Thanks, NeilBrown --Sig_/1V3/WbYw=2yjZZRAz0HW=4H Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iQIVAwUBUeSdnznsnt1WYoG5AQL+ERAAwEMpQ8eTpsHxAfzEDPzgxd9WKkwB1qUs dkvN0mHJMBwjKKuIlWT1Hl5CDD1nXDAJ/Q5Qh1B8dcja0WSjvTG12bptp56XpZIk WCWorPxuQNJrbOhg8KBhoZrPL4q3FS7N56vhxvuhuzDfhMQa34FS6QYHHeCoBPGR 6v9E4+GzpBD/9wwAX0X8MPmQqTPPT5xZ6If+VhJuCZYMMp3v6ocrzf4PdIcmNNqG lVy7W8W77d9FKTC2xQoBem4w/Q45a9nkcV5yY4xsdS7i29cqOpWTa95n0s3uTniT 6ykPiiJdNWnzUIg9pT9+1uHbOKEeeD/xrDznVFuZcjkvxqJzLMbPjfpbwQQGe4nC PNAE1aVoePDnoSN5nZOBS7t5Zxe1k4fOKIRffjJyR2PPc+T1w0U5Gg8kR6xApEwg J3RfaF6766QohL35aoEo7XgnE8XTI76ncr8FFTIbT/Xskd8wu3aeRwEP2Cp2Qkaf L7U3aSC6IIj5egzZWL/8vtYDM5U9a2E6UtumoQCJkewmqErHi5Xu4EOlo8kJSa2X H0fYiDO63g5gDrKmxK1ySPVWClVAjVqETuPCqbNsgy0TLWZRAy4l9N8JCmf3uP1M 5j4VEzWevUWceExw73sWE7Ot0RTdgTWA1zsEYE2L7lsLChebTNWog01JmXc1ivyb NvyWTBGznUo= =T/gP -----END PGP SIGNATURE----- --Sig_/1V3/WbYw=2yjZZRAz0HW=4H--