From owner-freebsd-performance@FreeBSD.ORG Tue Jan 3 22:16:13 2012 Return-Path: Delivered-To: performance@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 3A1071065675 for ; Tue, 3 Jan 2012 22:16:13 +0000 (UTC) (envelope-from david@catwhisker.org) Received: from albert.catwhisker.org (m209-73.dsl.rawbw.com [198.144.209.73]) by mx1.freebsd.org (Postfix) with ESMTP id 14F2F8FC1B for ; Tue, 3 Jan 2012 22:16:12 +0000 (UTC) Received: from albert.catwhisker.org (localhost [127.0.0.1]) by albert.catwhisker.org (8.14.5/8.14.5) with ESMTP id q03LdSw7020558 for ; Tue, 3 Jan 2012 13:39:28 -0800 (PST) (envelope-from david@albert.catwhisker.org) Received: (from david@localhost) by albert.catwhisker.org (8.14.5/8.14.5/Submit) id q03LdS4J020557 for performance@freebsd.org; Tue, 3 Jan 2012 13:39:28 -0800 (PST) (envelope-from david) Date: Tue, 3 Jan 2012 13:39:28 -0800 From: David Wolfskill To: performance@freebsd.org Message-ID: <20120103213928.GP1733@albert.catwhisker.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="4SRTEifjNkXp0Rce" Content-Disposition: inline User-Agent: Mutt/1.4.2.3i Cc: Subject: vm.exec_map_entries vs. hw.ncpu vs. ...? X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 03 Jan 2012 22:16:13 -0000 --4SRTEifjNkXp0Rce Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable A colleague at work has been researching the nature of some issues we're seeing in a FreeBSD/amd64 release/8.2.0 environment in which amd (which is providing services to a jail, where the "useful work" actually gets done) is apparently failing (on occasion) to perform the work it is supposed to do because vm.exec_map_entries is set too low. vm.exec_map_entries default value is 16 -- see src/sys/vm/vm_init.c:91-94: static int exec_map_entries =3D 16; TUNABLE_INT("vm.exec_map_entries", &exec_map_entries); SYSCTL_INT(_vm, OID_AUTO, exec_map_entries, CTLFLAG_RD, &exec_map_entries, = 0, "Maximum number of simultaneous execs"); We had not previously modified the setting. The machines in question are dual-package, 6-core machines with Intel's SMT (Simultaneous Multi-Threading) enabled, so hw.ncpu is 24. Is it reasonable for exec_map_entries to be thus initialized, independently of number of logical cores, kern.maxusers, amount of memory, or anything else? Are there guidelines or suggestions for setting it? Apparently each entry consumes a bit over 200KB, so making it arbitrarily large is probably not a good idea. :-} I don't see it mentioned in tuning(7). Thanks for any inisight. Peace, david --=20 David H. Wolfskill david@catwhisker.org Depriving a girl or boy of an opportunity for education is evil. See http://www.catwhisker.org/~david/publickey.gpg for my public key. --4SRTEifjNkXp0Rce Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (FreeBSD) iEYEARECAAYFAk8DdY8ACgkQmprOCmdXAD0uRgCfZKODGaZcA/ZsB73aqYHRTveq XbEAoIMqTRc8vMGP8dOMg8yab2m7BG5w =7beb -----END PGP SIGNATURE----- --4SRTEifjNkXp0Rce--