From owner-svn-src-head@FreeBSD.ORG Wed Aug 11 12:34:33 2010 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 90EC61065674; Wed, 11 Aug 2010 12:34:33 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from mail.zoral.com.ua (mx0.zoral.com.ua [91.193.166.200]) by mx1.freebsd.org (Postfix) with ESMTP id 0A9078FC21; Wed, 11 Aug 2010 12:34:32 +0000 (UTC) Received: from deviant.kiev.zoral.com.ua (root@deviant.kiev.zoral.com.ua [10.1.1.148]) by mail.zoral.com.ua (8.14.2/8.14.2) with ESMTP id o7BCYV6Q005068 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Wed, 11 Aug 2010 15:34:31 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: from deviant.kiev.zoral.com.ua (kostik@localhost [127.0.0.1]) by deviant.kiev.zoral.com.ua (8.14.4/8.14.4) with ESMTP id o7BCYV2U079675; Wed, 11 Aug 2010 15:34:31 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.14.4/8.14.4/Submit) id o7BCYUdq079674; Wed, 11 Aug 2010 15:34:30 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: deviant.kiev.zoral.com.ua: kostik set sender to kostikbel@gmail.com using -f Date: Wed, 11 Aug 2010 15:34:30 +0300 From: Kostik Belousov To: Attilio Rao Message-ID: <20100811123430.GK2396@deviant.kiev.zoral.com.ua> References: <201008111051.o7BApRp4028538@svn.freebsd.org> <20100811105739.GJ2396@deviant.kiev.zoral.com.ua> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="STPqjqpCrtky8aYs" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.3i X-Virus-Scanned: clamav-milter 0.95.2 at skuns.kiev.zoral.com.ua X-Virus-Status: Clean Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r211176 - in head/sys: amd64/amd64 i386/i386 X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 11 Aug 2010 12:34:33 -0000 --STPqjqpCrtky8aYs Content-Type: text/plain; charset=koi8-r Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Aug 11, 2010 at 01:21:46PM +0200, Attilio Rao wrote: > 2010/8/11 Kostik Belousov : > > On Wed, Aug 11, 2010 at 10:51:27AM +0000, Attilio Rao wrote: > >> Author: attilio > >> Date: Wed Aug 11 10:51:27 2010 > >> New Revision: 211176 > >> URL: http://svn.freebsd.org/changeset/base/211176 > >> > >> Log: > >> =9A IPI handlers may run generally with interrupts disabled because th= ey > >> =9A are served via an interrupt gate. > >> > >> =9A However, that doesn't explicitly prevent preemption and thread > >> =9A migration thus scheduler pinning may be necessary in some handlers. > >> =9A Fix that. > > > > How the preemption is supposed to happen ? Aside from the explicit > > calls to mi_switch() from e.g. critical_exit(). >=20 > IIRC it should be hardclock() willing to schedule the softclock(). It > is the critical_exit() in the thread_unlock() that may trigger it > (sorry for not digging more, it was a while back that I hacked this > part, but I guess you can verify on your own). > We already have other points within the kernel that take care of > dealing with preemption/migration like lapic_handle_timer(), for > example. Right, and if the interrupts are indeed disabled, I do not see how the preemption may be triggered in the fragments like cpu =3D PCPU_GET(cpuid); cpumask =3D PCPU_GET(cpumask); --STPqjqpCrtky8aYs Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (FreeBSD) iEYEARECAAYFAkximNYACgkQC3+MBN1Mb4hokwCfVKvpntMv62suh6fSzcoc3jfY Q9sAoJiLrEVzHRQAc/enXp5bNnNPGlnK =OPog -----END PGP SIGNATURE----- --STPqjqpCrtky8aYs--