From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758544Ab0JZO5Q (ORCPT ); Tue, 26 Oct 2010 10:57:16 -0400 Received: from hera.kernel.org ([140.211.167.34]:58527 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751529Ab0JZO5P (ORCPT ); Tue, 26 Oct 2010 10:57:15 -0400 Message-ID: <4CC6EC31.4090304@kernel.org> Date: Tue, 26 Oct 2010 16:56:49 +0200 From: Tejun Heo User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); en-US; rv:1.9.2.11) Gecko/20101013 Lightning/1.0b2 Thunderbird/3.1.5 MIME-Version: 1.0 To: David Howells CC: torvalds@osdl.org, akpm@linux-foundation.org, linux-am33-list@redhat.com, linux-kernel@vger.kernel.org, Akira Takeuchi , Mark Salter Subject: Re: [PATCH] MN10300: Fix the PERCPU() alignment to allow for workqueues References: <4CC6C62F.1000804@kernel.org> <4CC69B22.2050708@kernel.org> <20101025224111.7798.38960.stgit@warthog.procyon.org.uk> <12101.1288088542@redhat.com> <14874.1288104642@redhat.com> In-Reply-To: <14874.1288104642@redhat.com> X-Enigmail-Version: 1.1.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Tue, 26 Oct 2010 14:56:51 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, David. On 10/26/2010 04:50 PM, David Howells wrote: >>> FRV's page size is 16KB, so on that we really don't want it to be >>> PAGE_SIZE. >> >> Why not? It's in the init section which will be freed anyway and with >> the kernel image compression it's not even gonna add any noticeable >> amount to the kernel image size. There isn't any benefit in using >> anything smaller than PAGE_SIZE for alignment. Also, percpu allocator >> guarantees alignment requirement upto PAGE_SIZE is honored. If the >> output section uses smaller alignment, the percpu AS will end up being >> misaligned. > > The bootloader we have doesn't do decompression. I see. :-( > On the other hand, does the PERCPU stuff need to be allocated space > in the image by the linker? Can it be initialised to anything other > than zeros? Sure, for example, in kernel/timer.c. static DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases; It doesn't seem too popular at this point tho. Thanks. -- tejun