From owner-svn-src-all@freebsd.org Sun Jan 26 09:48:44 2020 Return-Path: Delivered-To: svn-src-all@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 842E4237536; Sun, 26 Jan 2020 09:48:44 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from smtp.freebsd.org (smtp.freebsd.org [96.47.72.83]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "smtp.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4857P830N4z3JjR; Sun, 26 Jan 2020 09:48:44 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from dhcp-10-248-114-204.eduroam.wireless.private.cam.ac.uk (global-5-143.nat-2.net.cam.ac.uk [131.111.5.143]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client did not present a certificate) (Authenticated sender: jhb) by smtp.freebsd.org (Postfix) with ESMTPSA id CB5154A17; Sun, 26 Jan 2020 09:48:43 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Subject: Re: svn commit: r357051 - head/sys/dev/bge To: Gleb Smirnoff , Jeff Roberson Cc: Ryan Stone , src-committers , svn-src-all , svn-src-head References: <202001231636.00NGawrr080128@repo.freebsd.org> <20200123230546.GG1268@FreeBSD.org> <20200124012458.GI1268@FreeBSD.org> <20200124024356.GK1268@FreeBSD.org> <20200124033243.GL1268@FreeBSD.org> From: John Baldwin Openpgp: preference=signencrypt Autocrypt: addr=jhb@FreeBSD.org; keydata= mQGiBETQ+XcRBADMFybiq69u+fJRy/0wzqTNS8jFfWaBTs5/OfcV7wWezVmf9sgwn8TW0Dk0 c9MBl0pz+H01dA2ZSGZ5fXlmFIsee1WEzqeJzpiwd/pejPgSzXB9ijbLHZ2/E0jhGBcVy5Yo /Tw5+U/+laeYKu2xb0XPvM0zMNls1ah5OnP9a6Ql6wCgupaoMySb7DXm2LHD1Z9jTsHcAQMD /1jzh2BoHriy/Q2s4KzzjVp/mQO5DSm2z14BvbQRcXU48oAosHA1u3Wrov6LfPY+0U1tG47X 1BGfnQH+rNAaH0livoSBQ0IPI/8WfIW7ub4qV6HYwWKVqkDkqwcpmGNDbz3gfaDht6nsie5Z pcuCcul4M9CW7Md6zzyvktjnbz61BADGDCopfZC4of0Z3Ka0u8Wik6UJOuqShBt1WcFS8ya1 oB4rc4tXfSHyMF63aPUBMxHR5DXeH+EO2edoSwViDMqWk1jTnYza51rbGY+pebLQOVOxAY7k do5Ordl3wklBPMVEPWoZ61SdbcjhHVwaC5zfiskcxj5wwXd2E9qYlBqRg7QeSm9obiBCYWxk d2luIDxqaGJARnJlZUJTRC5vcmc+iGAEExECACAFAkTQ+awCGwMGCwkIBwMCBBUCCAMEFgID AQIeAQIXgAAKCRBy3lIGd+N/BI6RAJ9S97fvbME+3hxzE3JUyUZ6vTewDACdE1stFuSfqMvM jomvZdYxIYyTUpC5Ag0ERND5ghAIAPwsO0B7BL+bz8sLlLoQktGxXwXQfS5cInvL17Dsgnr3 1AKa94j9EnXQyPEj7u0d+LmEe6CGEGDh1OcGFTMVrof2ZzkSy4+FkZwMKJpTiqeaShMh+Goj XlwIMDxyADYvBIg3eN5YdFKaPQpfgSqhT+7El7w+wSZZD8pPQuLAnie5iz9C8iKy4/cMSOrH YUK/tO+Nhw8Jjlw94Ik0T80iEhI2t+XBVjwdfjbq3HrJ0ehqdBwukyeJRYKmbn298KOFQVHO EVbHA4rF/37jzaMadK43FgJ0SAhPPF5l4l89z5oPu0b/+5e2inA3b8J3iGZxywjM+Csq1tqz hltEc7Q+E08AAwUIAL+15XH8bPbjNJdVyg2CMl10JNW2wWg2Q6qdljeaRqeR6zFus7EZTwtX sNzs5bP8y51PSUDJbeiy2RNCNKWFMndM22TZnk3GNG45nQd4OwYK0RZVrikalmJY5Q6m7Z16 4yrZgIXFdKj2t8F+x613/SJW1lIr9/bDp4U9tw0V1g3l2dFtD3p3ZrQ3hpoDtoK70ioIAjjH aIXIAcm3FGZFXy503DOA0KaTWwvOVdYCFLm3zWuSOmrX/GsEc7ovasOWwjPn878qVjbUKWwx Q4QkF4OhUV9zPtf9tDSAZ3x7QSwoKbCoRCZ/xbyTUPyQ1VvNy/mYrBcYlzHodsaqUDjHuW+I SQQYEQIACQUCRND5ggIbDAAKCRBy3lIGd+N/BCO8AJ9j1dWVQWxw/YdTbEyrRKOY8YZNwwCf afMAg8QvmOWnHx3wl8WslCaXaE8= Message-ID: <6a5485eb-8623-3316-0385-b0cda1624b05@FreeBSD.org> Date: Sun, 26 Jan 2020 09:48:42 +0000 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:60.0) Gecko/20100101 Thunderbird/60.9.1 MIME-Version: 1.0 In-Reply-To: <20200124033243.GL1268@FreeBSD.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 26 Jan 2020 09:48:44 -0000 On 1/23/20 7:32 PM, Gleb Smirnoff wrote: > On Thu, Jan 23, 2020 at 05:09:14PM -1000, Jeff Roberson wrote: > J> While we don't have a policy strictly requiring reviews it is the norm to > J> have substantial changes socialized and reviewed. I appreciate the work > J> that you are doing but it likely should've been discussed somewhere > J> more publicly. I apologized if I missed it but I don't see reference to > J> anything. > > That was https://reviews.freebsd.org/D23242 A review alone isn't sufficient for large, sweeping changes in my mind. For major changes, a thread on arch@ or net@ or the like is probably more appropriate. You can include a link to a review or git branch, etc. in that e-mail, but phabricator aren't as well suited to higher-level design-review type discussion, more for implementation-review. > J> Architecturally I am more concerned with the coarseness of net_epoch and > J> the duration of hold becoming a resource utilization problem in high > J> turn-over workloads. Like short connection tcp. Has anyone done > J> substantial testing here? epoch as it is today will hold every free > J> callback for a minimum of several clock ticks and a maximum of 2x the > J> duration of the longest epoch section time. With preemption, etc. this > J> could be 100s of ms of PCBs held. > > We also are concerned about that theoretically. Haven't yet seen effect > in practice, but our sessions are mostly longer living. First we have the > tunable to limit batching. Second, there are some ideas on how to improve > the garbage collector performance if it becomes an issue. There are other workloads than Netflix. ;) Verisign has incredibly short-lived connections with very high turnover. I think though that they have already abandoned the in-tree network stack for a userland stack built on netmap. Still, I think that there are probably other FreeBSD users that are probably somewhere in the middle that shouldn't be ignored. Packet batching would not be impossible by simply using m_nextpkt chains in mbufs passed up to ether_input and having ether_input pass them in a loop to the next higher loop (as a first step). That would reduce unlock/lock operations in drivers (for those still using locks on receive) as well as permitting ether_input to process batches under a single epoch invocation. -- John Baldwin