From owner-svn-src-all@freebsd.org Sun May 19 05:46:26 2019 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 1F7A315A3E0D; Sun, 19 May 2019 05:46:26 +0000 (UTC) (envelope-from imp@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (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 "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 3533B807FD; Sun, 19 May 2019 05:46:25 +0000 (UTC) (envelope-from imp@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 0B8002A99; Sun, 19 May 2019 05:46:25 +0000 (UTC) (envelope-from imp@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id x4J5kOPG027341; Sun, 19 May 2019 05:46:24 GMT (envelope-from imp@FreeBSD.org) Received: (from imp@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id x4J5kOkO027339; Sun, 19 May 2019 05:46:24 GMT (envelope-from imp@FreeBSD.org) Message-Id: <201905190546.x4J5kOkO027339@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: imp set sender to imp@FreeBSD.org using -f From: Warner Losh Date: Sun, 19 May 2019 05:46:24 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r347966 - head/share/man/man4 X-SVN-Group: head X-SVN-Commit-Author: imp X-SVN-Commit-Paths: head/share/man/man4 X-SVN-Commit-Revision: 347966 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 3533B807FD X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-2.95 / 15.00]; local_wl_from(0.00)[FreeBSD.org]; NEURAL_HAM_MEDIUM(-1.00)[-0.999,0]; NEURAL_HAM_SHORT(-0.95)[-0.947,0]; ASN(0.00)[asn:11403, ipnet:2610:1c1:1::/48, country:US]; NEURAL_HAM_LONG(-1.00)[-1.000,0] 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, 19 May 2019 05:46:26 -0000 Author: imp Date: Sun May 19 05:46:24 2019 New Revision: 347966 URL: https://svnweb.freebsd.org/changeset/base/347966 Log: Add note about nvd / nda selection. Noticed by: cem@ Modified: head/share/man/man4/nvme.4 Modified: head/share/man/man4/nvme.4 ============================================================================== --- head/share/man/man4/nvme.4 Sun May 19 04:56:02 2019 (r347965) +++ head/share/man/man4/nvme.4 Sun May 19 05:46:24 2019 (r347966) @@ -33,7 +33,7 @@ .\" .\" $FreeBSD$ .\" -.Dd December 7, 2018 +.Dd May 18, 2019 .Dt NVME 4 .Os .Sh NAME @@ -119,6 +119,38 @@ hw.nvme.force_intx=1 .Ed .Pp Note that use of INTx implies disabling of per-CPU I/O queue pairs. +.Pp +The +.Xr nvd 4 +driver is used to provide a disk driver to the system by default. +The +.Xr nda 4 +driver can also be used instead. +The +.Xr nvd 4 +driver performs better with smaller transactions and few TRIM +commands. +It sends all commands directly the drive immediately. +The +.Xr nda 4 +driver performs better with larger transactions and also collapses +TRIM commands giving better performance. +It can queue commands to the drive; combine +.Dv BIO_DELETE +commands into a single trip; and +use the CAM I/O scheduler to bias one type of operation over another. +To select the +.Xr nda 4 +driver, set the following tunable value in +.Xr loader.conf 5 : +.Bd -literal -offset indent +hw.nvme.use_nvd=0 +.Ed +.Pp +This value may also be set in the kernel config file with +.Bd -literal -offset indent +.Cd options NVME_USE_NVD=0 +.Ed .Sh SYSCTL VARIABLES The following controller-level sysctls are currently implemented: .Bl -tag -width indent