From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 11 Dec 2002 11:13:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 11 Dec 2002 11:13:29 -0500 Received: from harpo.it.uu.se ([130.238.12.34]:34231 "EHLO harpo.it.uu.se") by vger.kernel.org with ESMTP id ; Wed, 11 Dec 2002 11:13:28 -0500 Date: Wed, 11 Dec 2002 17:21:14 +0100 (MET) From: Mikael Pettersson Message-Id: <200212111621.RAA16124@harpo.it.uu.se> To: perfctr-devel@lists.sourceforge.net Subject: perfctr-2.4.3 released Cc: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org perfctr-2.4.3 is now available at the usual place: http://www.csd.uu.se/~mikpe/linux/perfctr/ Users of hyper-threaded Pentium 4s (Xeons) are strongly recommended to upgrade to this release. Older releases may silently malfunction due to the resource conflicts mentioned in the CHANGES extract below. Version 2.4.3, 2002-12-11 - Support for hyper-threaded Pentium 4s added. In a HT P4, the two logical processors share the performance counter state. HT P4s are therefore _asymmetric_ multi-processors, and the driver enforces CPU affinity masks on users of per-process performance counters to avoid resource conflicts. (Users are restricted to logical processor #0 in each physical CPU.) Limitations: * The kernel mechanism for updating a process' CPU affinity mask uses no or very weak locking, which makes certain race conditions possible that can break the driver's CPU affinity mask restrictions. For now, users should NOT use the sched_setaffinity() system call on processes using per-process performance counters. * Global-mode performance counters don't work on HT P4s due to limitations in the API. This will be fixed in perfctr-2.5. * 2.2 kernels don't have CPU affinity masks, and therefore can't support HT P4s. / Mikael Pettersson