From owner-freebsd-scsi@freebsd.org Wed Jul 29 03:58:40 2015 Return-Path: Delivered-To: freebsd-scsi@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 45D1A9AB4B1 for ; Wed, 29 Jul 2015 03:58:40 +0000 (UTC) (envelope-from scott4long@yahoo.com) Received: from nm21-vm7.bullet.mail.gq1.yahoo.com (nm21-vm7.bullet.mail.gq1.yahoo.com [98.136.217.54]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 159DF1197 for ; Wed, 29 Jul 2015 03:58:39 +0000 (UTC) (envelope-from scott4long@yahoo.com) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1438142216; bh=Iy5GJLAsvHW9m1kN7RjZM2zHQJbDHwhCJ55MeqWSnC8=; h=Subject:From:In-Reply-To:Date:Cc:References:To:From:Subject; b=hrT4yonLdcxHv795E9GEt5VMx45oVnrkcWhrrW8wDMI7SLYWhFH1qKZyagDExWe94udDZUcWbz+orJdgvVjJW7A7A/X631t7BcMfHEh1VbyP5gnfqwWOPuzGZgSfbl7v+qbakDmFUYvTZwtx4axPgw/2by3ikQv88syonnn2UOMBgwmS8WBhoLTwk45w7acYeBHFSUH4DI4Utd7zIL5RE+i3w1Lfp1FVQyXUF+heTQCO/cg8+dLgK8iIqYwQpOHURzQzYQ+aG1spNC5dpMzebYRqiv1me3zrUSu+QEqPfDBVeKAoQ0spUZShKktXCTRZgruzMQyKd2mtmxD5li2+Yg== Received: from [98.137.12.189] by nm21.bullet.mail.gq1.yahoo.com with NNFMP; 29 Jul 2015 03:56:56 -0000 Received: from [208.71.42.214] by tm10.bullet.mail.gq1.yahoo.com with NNFMP; 29 Jul 2015 03:56:56 -0000 Received: from [127.0.0.1] by smtp225.mail.gq1.yahoo.com with NNFMP; 29 Jul 2015 03:56:56 -0000 X-Yahoo-Newman-Id: 254314.17331.bm@smtp225.mail.gq1.yahoo.com X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: 1043a.4VM1nnnEgI_YQKah5.pDtxTOQ2Gk8rb0bEv9AjlxU C0rvwanwEoCP3mEL9WourMrjFz5TA6ac5KGnv5UBdV7byzAyXFZgL6CxFXwB DWw9Ik9No39QHxWhEUR.pm6dY3Vbzr.R_U01l3ifRknmspTMkqbnLs7ht_Se NxnwOMVs.qrAYyA4Tlp165R5ZLfSrdetQu8M4zFCJVU6OLJt35xdn9a0.nv0 .MGW6vSoyHo37ot1yRo6GkR9wWakO0stfhhujja02uoztpfEl3ZX6nhnxucM t6Mu0Caum9GzuO1wafclkfgUjja3bqTFk20wDELoswJ4lYTsjswtAHV5iF3G 9nNlSS5GV43OFnt4OCuDeQ5GXoBIoXjNp8tMgGsgZCx9sFHI9CPMAwQXQbWa TwdJgBZzSuRVGVxoZLsXA8wg.6pZaKZ7hm2Ks2S.HGNNEHNgfRlKndj6yBO4 SKHiO6IXv3AKzGYExp776o1cIIPv0JvAK19YBnqNLZHUhXQCN8spxBiTQPCR peJVgxox7.5chsAyVAgCivDSfP1U9Cg-- X-Yahoo-SMTP: clhABp.swBB7fs.LwIJpv3jkWgo2NU8- Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2098\)) Subject: Re: dmesg output not as expected From: Scott Long In-Reply-To: Date: Tue, 28 Jul 2015 21:56:54 -0600 Cc: freebsd-scsi@freebsd.org Content-Transfer-Encoding: quoted-printable Message-Id: <27741F67-95F8-4EEF-B42F-E80626799FCB@yahoo.com> References: <5A302DC6-C3EF-4DB1-8AD1-A0314C048A28@langille.org> To: Dan Langille X-Mailer: Apple Mail (2.2098) X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 29 Jul 2015 03:58:40 -0000 > On Jul 28, 2015, at 8:18 PM, Dan Langille wrote: >=20 > After rebooting this server, I see this in /var/run/dmesg. Why does = it change? >=20 > ch0 at mpt0 bus 0 scbus14 target 3 lun 0 > ch0: Removable Changer SCSI-2 device > ch0: Serial Number 3G22JJP38S46 > ch0: 20.000MB/s transfers (10.000MHz DT, offset 15, 16bit) > ch0: 25 slots, 1 drive, 1 picker, 1 portal > ch0: quirks=3D0x2 >=20 > I was hoping to get more through put on this newer system with a = different card. =46rom what I see, my speed is only half of what it = was. >=20 > I'm using a PCI-E 3.0 X8 (in X16) slot. Have I missing something? >=20 The LSI controllers do Domain Validation. That means that they send a = series of test commands to each target to try to determine a safe speed = to negotiate to. The theory is that these test commands will determine = whether the target=E2=80=99s speed needs to be downshifted in order to = avoid problems with bad cables and bad connectors. It=E2=80=99s part of = the Ultra320 spec, and I think it was in the Ultra160 spec too, but was = rarely implemented there. It=E2=80=99s possible that the DV routine is = telling the card that these devices need to have their negotiated speed = reduced, and that the results it gets are a bit on-the-fence at times = and cause different observed speeds. It=E2=80=99s been a long time since I worked with DV, so my memory is a = bit fuzzy. The Adaptec hardware never did DV other than a really simple = algorithm in the BIOS for the U320 cards, and I=E2=80=99m pretty sure = that the Symbios cards pre-date DV all-together. I think that the MPT = controllers do DV in the firmware at boot, and the driver just reads the = results and uses that for the default negotiation settings. I don=E2=80=99= t see much in the MPT driver for debugging this, but I recall that the = DV algorithm that LSI used was pretty naive and overly-aggressive at = forcing down negotiation. You might want to look at what options the = LSI BIOS offers, or if you can use camcontrol to change the negotiation = up to where you think it should be. Scott