From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752460AbZIWWCb (ORCPT ); Wed, 23 Sep 2009 18:02:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752249AbZIWWCa (ORCPT ); Wed, 23 Sep 2009 18:02:30 -0400 Received: from hera.kernel.org ([140.211.167.34]:37502 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751400AbZIWWC3 (ORCPT ); Wed, 23 Sep 2009 18:02:29 -0400 Message-ID: <4ABA9B14.20904@kernel.org> Date: Thu, 24 Sep 2009 07:03:00 +0900 From: Tejun Heo User-Agent: Thunderbird 2.0.0.23 (X11/20090817) MIME-Version: 1.0 To: Christoph Lameter CC: Nick Piggin , Tony Luck , Fenghua Yu , linux-ia64 , Ingo Molnar , Rusty Russell , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/4] ia64: allocate percpu area for cpu0 like percpu areas for other cpus References: <1253605214-23210-1-git-send-email-tj@kernel.org> <1253605214-23210-3-git-send-email-tj@kernel.org> <4AB983B6.6050203@kernel.org> <4ABA2A3A.6020308@kernel.org> In-Reply-To: X-Enigmail-Version: 0.95.7 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Wed, 23 Sep 2009 22:02:13 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Christoph Lameter wrote: > On Wed, 23 Sep 2009, Tejun Heo wrote: > >> any special handling. What problems are you seeing? > > per cpu variable access on IA64 does not use the percpu_offset for the > calculation of the current per cpu data area. Its using a virtual mapping. > > How does the new percpu allocator support this? Does it use different > methods of access for static and dynamic percpu access? That's only when __ia64_per_cpu_var() macro is used in arch code which always references static perpcu variable in the kernel image which falls inside PERCPU_PAGE_SIZE. For everything else, __my_cpu_offset is defined as __ia64_per_cpu_var(local_per_cpu_offset) and regular pointer offsetting is used. Thanks. -- tejun From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Date: Wed, 23 Sep 2009 22:03:00 +0000 Subject: Re: [PATCH 2/4] ia64: allocate percpu area for cpu0 like percpu areas Message-Id: <4ABA9B14.20904@kernel.org> List-Id: References: <1253605214-23210-1-git-send-email-tj@kernel.org> <1253605214-23210-3-git-send-email-tj@kernel.org> <4AB983B6.6050203@kernel.org> <4ABA2A3A.6020308@kernel.org> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Christoph Lameter Cc: Nick Piggin , Tony Luck , Fenghua Yu , linux-ia64 , Ingo Molnar , Rusty Russell , linux-kernel@vger.kernel.org Christoph Lameter wrote: > On Wed, 23 Sep 2009, Tejun Heo wrote: > >> any special handling. What problems are you seeing? > > per cpu variable access on IA64 does not use the percpu_offset for the > calculation of the current per cpu data area. Its using a virtual mapping. > > How does the new percpu allocator support this? Does it use different > methods of access for static and dynamic percpu access? That's only when __ia64_per_cpu_var() macro is used in arch code which always references static perpcu variable in the kernel image which falls inside PERCPU_PAGE_SIZE. For everything else, __my_cpu_offset is defined as __ia64_per_cpu_var(local_per_cpu_offset) and regular pointer offsetting is used. Thanks. -- tejun