From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: + ignore-stolen-time-in-the-softlockup-watchdog-fix.patch added to -mm tree Date: Tue, 24 Apr 2007 19:14:25 -0700 Message-ID: <20070424191425.28a55eb6.akpm@linux-foundation.org> References: <200704242045.l3OKjD9N018856@shell0.pdx.osdl.net> <17966.45949.796715.978244@cargo.ozlabs.ibm.com> Reply-To: linux-kernel@vger.kernel.org Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from smtp1.linux-foundation.org ([65.172.181.25]:59617 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161823AbXDYCPZ (ORCPT ); Tue, 24 Apr 2007 22:15:25 -0400 In-Reply-To: <17966.45949.796715.978244@cargo.ozlabs.ibm.com> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: Paul Mackerras Cc: mm-commits@vger.kernel.org, clalance@redhat.com, dada1@cosmosbay.com, dhecht@vmware.com, jeremy@goop.org, jmorris@namei.org, johnstul@us.ibm.com, mingo@elte.hu, prarit@redhat.com, ricklind@us.ibm.com, schwidefsky@de.ibm.com, tglx@linutronix.de, zach@vmware.com On Wed, 25 Apr 2007 11:48:45 +1000 Paul Mackerras wrote: > akpm@linux-foundation.org writes: > > > Avoid reevaluating smp_processor_id() > > > int this_cpu = smp_processor_id(); > > - unsigned long touch_timestamp = __get_cpu_var(touch_timestamp); > > + unsigned long touch_timestamp = per_cpu(touch_timestamp, this_cpu); > > This is actually worse on those cpus that have a fast way to get to > the current cpu's per-cpu data. > The patch adds 4 bytes (strange number) to powerpc text and removes 32 from i386's. A net win, I guess. i386 now has a considerably better smp_processor_id(), but no special-case handling of per-cpu data. Maybe Jeremy has plans to move i386's per-cpu data into the pda also?