From owner-freebsd-hackers@freebsd.org Wed Jun 15 12:17:04 2016 Return-Path: Delivered-To: freebsd-hackers@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 DFB0DA1D1E5 for ; Wed, 15 Jun 2016 12:17:04 +0000 (UTC) (envelope-from freebsd-listen@fabiankeil.de) Received: from smtprelay02.ispgateway.de (smtprelay02.ispgateway.de [80.67.18.44]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id A781A1A1C for ; Wed, 15 Jun 2016 12:17:04 +0000 (UTC) (envelope-from freebsd-listen@fabiankeil.de) Received: from [78.35.172.85] (helo=fabiankeil.de) by smtprelay02.ispgateway.de with esmtpsa (TLSv1.2:AES128-GCM-SHA256:128) (Exim 4.84) (envelope-from ) id 1bD9bz-0006sn-Sx for freebsd-hackers@freebsd.org; Wed, 15 Jun 2016 14:07:59 +0200 Date: Wed, 15 Jun 2016 14:05:16 +0200 From: Fabian Keil To: freebsd-hackers@freebsd.org Subject: vnlru_proc() draining unrelated uma zones Message-ID: <20160615140516.3cba6001@fabiankeil.de> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; boundary="Sig_/ERk0lYNaHqqLuRujEm_vn6k"; protocol="application/pgp-signature" X-Df-Sender: Nzc1MDY3 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 15 Jun 2016 12:17:05 -0000 --Sig_/ERk0lYNaHqqLuRujEm_vn6k Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable While looking into two uma-related issues[0] I noticed that vnlru_proc() is calling uma_reclaim() even though the intention seems to be to merely drain the vnode-related zones. According to uma.h, uma_reclaim() "should only be called by the page out daemon", presumably because of the overhead and side-effects. I've been using this patch for a couple of weeks and didn't notice any regressions: diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c index 2767826..2c65ce1 100644 --- a/sys/kern/vfs_subr.c +++ b/sys/kern/vfs_subr.c @@ -1107,8 +1107,10 @@ vnlru_proc(void) vfs_unbusy(mp); } mtx_unlock(&mountlist_mtx); - if (onumvnodes > desiredvnodes && numvnodes <=3D desiredvno= des) - uma_reclaim(); + if (onumvnodes > desiredvnodes && numvnodes <=3D desiredvno= des) { + zone_drain(vnode_zone); + zone_drain(vnodepoll_zone); + } if (done =3D=3D 0) { if (force =3D=3D 0 || force =3D=3D 1) { force =3D 2; It also didn't seem to noticeable affect the issues I was investigating (the code is rarely executed on my systems), but calling uma_reclaim() still seems strange to me. Am I missing something? Fabian [0] "Prevent deadlocks when paging on GELI-encrypted devices": https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D209759 "[...] connections time out/ssh results in 'broken pipe'": https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D209680 --Sig_/ERk0lYNaHqqLuRujEm_vn6k Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iEYEARECAAYFAldhRH0ACgkQBYqIVf93VJ16qgCfbyuMri2/5q+1vll5GYNcwJJZ GCgAnjro8MsibfgqXax/35n3mdg8yDni =NuTq -----END PGP SIGNATURE----- --Sig_/ERk0lYNaHqqLuRujEm_vn6k--