From owner-freebsd-current@freebsd.org Fri Apr 15 16:26:28 2016 Return-Path: Delivered-To: freebsd-current@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 90904AEE368 for ; Fri, 15 Apr 2016 16:26:28 +0000 (UTC) (envelope-from allanjude@freebsd.org) Received: from mx1.scaleengine.net (mx1.scaleengine.net [209.51.186.6]) by mx1.freebsd.org (Postfix) with ESMTP id 5483B1782 for ; Fri, 15 Apr 2016 16:26:27 +0000 (UTC) (envelope-from allanjude@freebsd.org) Received: from [10.1.1.2] (unknown [10.1.1.2]) (Authenticated sender: allanjude.freebsd@scaleengine.com) by mx1.scaleengine.net (Postfix) with ESMTPSA id 89F89D476 for ; Fri, 15 Apr 2016 16:26:21 +0000 (UTC) Subject: Re: Heads up To: freebsd-current@freebsd.org References: From: Allan Jude Message-ID: <57111629.6070606@freebsd.org> Date: Fri, 15 Apr 2016 12:26:17 -0400 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.7.2 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="kUTTLi1D2VgF4kr7qkhrnOjaDsPvJMrIb" X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 15 Apr 2016 16:26:28 -0000 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --kUTTLi1D2VgF4kr7qkhrnOjaDsPvJMrIb Content-Type: multipart/mixed; boundary="cFhrscBwWNNmCPnKdqIPpAUlrkEk5s9vv" From: Allan Jude To: freebsd-current@freebsd.org Message-ID: <57111629.6070606@freebsd.org> Subject: Re: Heads up References: In-Reply-To: --cFhrscBwWNNmCPnKdqIPpAUlrkEk5s9vv Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable On 2016-04-15 12:13, Maxim Sobolev wrote: > Great, work Warner, thanks! Small note, though. The CAM_IOSCHED_NETFLIX= > seems like a quite poor name for a kernel option. IMHO there is no good= > reason for polluting it with the name of the company that sponsored the= > development. I don't think we have any precedents of doing this unless = the > option is related to a piece of hardware that the company makes, and it= 's > not the case here. Apart from "coolness" factor as far as I understand = that > _NETFLIX suffix does not give any tangible benefit for anybody reading > kernel config and trying to understand what this option actually does. > CAM_IOSCHED_SSDNG or something would be better IMHO. Just my $0.02. >=20 > -Max The tuning that CAM_IOCHED_NETFLIX does is not generally applicable to all SSDs, it is very specific to netflix style workloads, where you want to rate-limit writes to preserve low latency for reads. Most workflows, like a database on an SSD, will be the opposite, wanting to prioritize writes over anything else. It is important to not give this scheduler a generic attractive name that will cause people to use it without understanding what its purpose is. The purpose is not 'better scheduling for SSDs', but rather 'scheduling for a latency sensitive read-mostly workload while updating a content library in the background' >=20 > On Thu, Apr 14, 2016 at 3:42 PM, Warner Losh wrote: >=20 >> The CAM I/O scheduler has been committed to current. This work is desc= ribed >> in https://people.freebsd.org/~imp/bsdcan2015/iosched-v3.pdf though th= e >> default scheduler doesn't change the default (old) behavior. >> >> One possible issue, however, is that it also enables NCQ Trims on ada = SSDs. >> There are a few rogue drives that claim support for this feature, but >> actually implement data corrupt instead of queued trims. The list of k= nown >> rogues is believed to be complete, but some caution is in order. >> >> Warner --=20 Allan Jude --cFhrscBwWNNmCPnKdqIPpAUlrkEk5s9vv-- --kUTTLi1D2VgF4kr7qkhrnOjaDsPvJMrIb Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (MingW32) iQIcBAEBAgAGBQJXERYsAAoJEBmVNT4SmAt+OcMQAK/2Tq5TS3FXCDF+h7vv1Ivu rhbz6nDHeb0Uf7RwVP9ZreOJ49kTvVkLWgWontr6bjKLBE37YyVPN82aLDYpw9yB +wLcWzde/Pgz6+qoDX2Atbn2DzGQFPyRFNb0HiAaC5NnrGvaHEon+GlE8ZMsyZOM Ro7L1mfUP9dAImi1Ie9Tn2h5E0irbWhnAgfL813ldCTTLuTMWQHhCCisDQDjfmHq BVxyq6+wjkDaUUCoMSTfpep/snfac4eCJvFgMHZ4+Q0fRqUNx+Ar6OjpTtPGdKim TmUOnob0QxgqpQX0jL/aQV3ceenCv/PXj4bbftCMxMoInMd/txtcndUz0e01sF4H ZCuwlQEuqOPwIQ5vUidfG9t5o1z5znE1BkfS9yj1xjrcsoxe7cVYO3XH+Ur2aThj 3rJjAz4adjEk1WTxGxYgLjk4ZvJZBCxbiGwLzVSUFaaCEfq3Th5iW6C/QEIc1RnD L8mhAwFDkPONAizk4lpLlzicWDmnStEdzs/TzpMxDhiNNY2YYZbGWwCBTBMCqyna ZNGdiz8tj2jS0uGvDEFA3ms1aw0iDslc7p+/DP++WdWiini2N2YFxnDDw3Mf529m 3m6EhLUr24h+kt2ktHksv1iEr10RZyXNUkifLZbN9p1+w+clhpoyCmVcWCdbnDpw y3cMrDUoCAfCV9sZA8ND =LtAH -----END PGP SIGNATURE----- --kUTTLi1D2VgF4kr7qkhrnOjaDsPvJMrIb--