From owner-freebsd-net@FreeBSD.ORG Sat Dec 22 07:03:27 2007 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E4AA816A41B; Sat, 22 Dec 2007 07:03:27 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from relay02.kiev.sovam.com (relay02.kiev.sovam.com [62.64.120.197]) by mx1.freebsd.org (Postfix) with ESMTP id 7B65F13C461; Sat, 22 Dec 2007 07:03:27 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from [212.82.216.226] (helo=deviant.kiev.zoral.com.ua) by relay02.kiev.sovam.com with esmtps (TLSv1:AES256-SHA:256) (Exim 4.67) (envelope-from ) id 1J5yOH-000HOX-D6; Sat, 22 Dec 2007 09:03:26 +0200 Received: from deviant.kiev.zoral.com.ua (kostik@localhost [127.0.0.1]) by deviant.kiev.zoral.com.ua (8.14.2/8.14.2) with ESMTP id lBM73IMb030376; Sat, 22 Dec 2007 09:03:18 +0200 (EET) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.14.2/8.14.2/Submit) id lBM73IJ3030375; Sat, 22 Dec 2007 09:03:18 +0200 (EET) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: deviant.kiev.zoral.com.ua: kostik set sender to kostikbel@gmail.com using -f Date: Sat, 22 Dec 2007 09:03:18 +0200 From: Kostik Belousov To: Mark Fullmer Message-ID: <20071222070318.GT57756@deviant.kiev.zoral.com.ua> References: <20071217102433.GQ25053@tnn.dglawrence.com> <20071220011626.U928@besplex.bde.org> <814DB7A9-E64F-4BCA-A502-AB5A6E0297D3@eng.oar.net> <20071219171331.GH25053@tnn.dglawrence.com> <20071221200810.GY16982@elvis.mu.org> <20071221234347.GS25053@tnn.dglawrence.com> <6D374B4C-0D98-4916-A762-7A85912B3058@splintered.net> <20071222053648.GQ57756@deviant.kiev.zoral.com.ua> <3647BB78-BA10-432B-A52B-04E402E155CC@splintered.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="N7HXVILz59yg1nI8" Content-Disposition: inline In-Reply-To: <3647BB78-BA10-432B-A52B-04E402E155CC@splintered.net> User-Agent: Mutt/1.4.2.3i X-Scanner-Signature: ebef06da57613c13a9510a9a5e517e93 X-DrWeb-checked: yes X-SpamTest-Envelope-From: kostikbel@gmail.com X-SpamTest-Group-ID: 00000000 X-SpamTest-Info: Profiles 1938 [Dec 21 2007] X-SpamTest-Info: helo_type=3 X-SpamTest-Info: {received from trusted relay: not dialup} X-SpamTest-Method: none X-SpamTest-Method: Local Lists X-SpamTest-Rate: 0 X-SpamTest-Status: Not detected X-SpamTest-Status-Extended: not_detected X-SpamTest-Version: SMTP-Filter Version 3.0.0 [0255], KAS30/Release Cc: freebsd-net@freebsd.org, freebsd-stable@freebsd.org Subject: Re: Packet loss every 30.999 seconds X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 22 Dec 2007 07:03:28 -0000 --N7HXVILz59yg1nI8 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Dec 22, 2007 at 01:28:31AM -0500, Mark Fullmer wrote: >=20 > On Dec 22, 2007, at 12:36 AM, Kostik Belousov wrote: > >Lets check whether the syncer is the culprit for you. > >Please, change the value of the syncdelay at the sys/kern/vfs_subr.c > >around the line 238 from 30 to some other value, e.g., 45. After that, > >check the interval of the effect you have observed. >=20 > Changed it to 13. Not sure if SYNCER_MAXDELAY also needed to be > increased if syncdelay was increased. >=20 > static int syncdelay =3D 13; /* max time to delay syncing = =20 > data */ >=20 > Test: >=20 > ; use vnodes > % find / -type f -print > /dev/null >=20 > ; verify > % sysctl vfs.numvnodes > vfs.numvnodes: 32128 >=20 > ; run packet loss test > now have periodic loss every 13994633us (13.99 seconds). >=20 > ; reduce # of vnodes with sysctl kern.maxvnodes=3D1000 > test now runs clean. Definitely syncer.=20 > > > >It would be interesting to check whether completely disabling the =20 > >syncer > >eliminates the packet loss, but such system have to be operated with > >extreme caution. Ok, no need to do this. As Bruce Evans noted, there is a vfs_msync() that do almost the same traversal of the vnodes. It was missed in the previous patch. Try this one. diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c index 3c2e1ed..6515d6a 100644 --- a/sys/kern/vfs_subr.c +++ b/sys/kern/vfs_subr.c @@ -2967,7 +2967,9 @@ vfs_msync(struct mount *mp, int flags) { struct vnode *vp, *mvp; struct vm_object *obj; + int yield_count; =20 + yield_count =3D 0; MNT_ILOCK(mp); MNT_VNODE_FOREACH(vp, mp, mvp) { VI_LOCK(vp); @@ -2996,6 +2998,12 @@ vfs_msync(struct mount *mp, int flags) MNT_ILOCK(mp); } else VI_UNLOCK(vp); + if (yield_count++ =3D=3D 500) { + MNT_IUNLOCK(mp); + yield_count =3D 0; + uio_yield(); + MNT_ILOCK(mp); + } } MNT_IUNLOCK(mp); } diff --git a/sys/ufs/ffs/ffs_vfsops.c b/sys/ufs/ffs/ffs_vfsops.c index cbccc62..9e8b887 100644 --- a/sys/ufs/ffs/ffs_vfsops.c +++ b/sys/ufs/ffs/ffs_vfsops.c @@ -1182,6 +1182,7 @@ ffs_sync(mp, waitfor, td) int secondary_accwrites; int softdep_deps; int softdep_accdeps; + int yield_count; struct bufobj *bo; =20 fs =3D ump->um_fs; @@ -1216,6 +1217,7 @@ loop: softdep_get_depcounts(mp, &softdep_deps, &softdep_accdeps); MNT_ILOCK(mp); =20 + yield_count =3D 0; MNT_VNODE_FOREACH(vp, mp, mvp) { /* * Depend on the mntvnode_slock to keep things stable enough @@ -1233,6 +1235,12 @@ loop: (IN_ACCESS | IN_CHANGE | IN_MODIFIED | IN_UPDATE)) =3D=3D 0 && vp->v_bufobj.bo_dirty.bv_cnt =3D=3D 0)) { VI_UNLOCK(vp); + if (yield_count++ =3D=3D 500) { + MNT_IUNLOCK(mp); + yield_count =3D 0; + uio_yield(); + MNT_ILOCK(mp); + } continue; } MNT_IUNLOCK(mp); --N7HXVILz59yg1nI8 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (FreeBSD) iD8DBQFHbLa1C3+MBN1Mb4gRAjZAAKDOZCUCmfjbFX61IvwpSDfMg8dTCgCgqxLE LsxaM+dv/WP5wHW2z1lYJZ8= =yi5I -----END PGP SIGNATURE----- --N7HXVILz59yg1nI8--