From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756968AbZEUAiR (ORCPT ); Wed, 20 May 2009 20:38:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755376AbZEUAiH (ORCPT ); Wed, 20 May 2009 20:38:07 -0400 Received: from mga03.intel.com ([143.182.124.21]:13481 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755247AbZEUAiG (ORCPT ); Wed, 20 May 2009 20:38:06 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.41,224,1241420400"; d="scan'208";a="145210756" Subject: Re: [GIT PATCH] x86,percpu: fix pageattr handling with remap allocator From: Suresh Siddha Reply-To: suresh.b.siddha@intel.com To: Tejun Heo Cc: "H. Peter Anvin" , "JBeulich@novell.com" , "andi@firstfloor.org" , "mingo@elte.hu" , "linux-kernel-owner@vger.kernel.org" , "tglx@linutronix.de" , "linux-kernel@vger.kernel.org" In-Reply-To: <4A149B89.3010104@kernel.org> References: <1242305390-21958-1-git-send-email-tj@kernel.org> <1242436626.27006.8623.camel@localhost.localdomain> <4A0ED8D8.2010303@kernel.org> <1242500964.27006.8636.camel@localhost.localdomain> <4A0F672A.3000309@kernel.org> <1242674444.27006.8691.camel@localhost.localdomain> <4A11B9E7.8010707@zytor.com> <1242680835.27006.8734.camel@localhost.localdomain> <4A120B47.8060200@kernel.org> <1242860470.27006.10106.camel@localhost.localdomain> <4A149B89.3010104@kernel.org> Content-Type: text/plain Organization: Intel Corp Date: Wed, 20 May 2009 17:36:03 -0700 Message-Id: <1242866163.27006.10125.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.24.1 (2.24.1-2.fc10) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2009-05-20 at 17:08 -0700, Tejun Heo wrote: > Heh... the problem is that unless I understand what you're trying to > achieve (and vice-versa), our discussion is likely to be riddled with > confusions, and currently either you're misunderstanding the whole > thing or I'm being slow (not too unusual :-). It would be nice to > determine which way it is. At the start of this, I was trying to see a way where we can use large page mappings for percpu areas and at the same time, avoid the complexity of cpa() that we are adding in this patchset. So, I was going down the path of exploiting your bootmem allocation for the first percpu chunk (as kernel identity mappings are already taken care by cpa()). > The dynamic onlining will probably use 4k pages so, yeah, it won't > have the alias issues but that's not the issue here, right? You can > already avoid aliasing that way by simply using 4k allocator from the > get-go. But now that I learnt about dynamic online allocation, can we avoid the complexity brought by this patchset, by simply using 4k allocator from get-go. i.e., can we drop this remap pageattr handling patchset and simply use 4k mapping for now? And move to dynamic allocation at a later point. This will simplify quite a bit of code. thanks, suresh