Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757350Ab3JNTKJ (ORCPT ); Mon, 14 Oct 2013 15:10:09 -0400 Received: from a9-50.smtp-out.amazonses.com ([54.240.9.50]:47737 "EHLO a9-50.smtp-out.amazonses.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756599Ab3JNTKH (ORCPT ); Mon, 14 Oct 2013 15:10:07 -0400 Date: Mon, 14 Oct 2013 19:04:05 +0000 From: Christoph Lameter X-X-Sender: cl@gentwo.org To: "Kirill A. Shutemov" cc: Andrew Morton , Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org Subject: Re: [PATCH 34/34] mm: dynamically allocate page->ptl if it cannot be embedded to struct page In-Reply-To: <20131014090437.F22CBE0090@blue.fi.intel.com> Message-ID: <00000141b85a90a0-7cf6bab0-4c17-4fc0-8224-74bbb1fc85ee-000000@email.amazonses.com> References: <1381428359-14843-1-git-send-email-kirill.shutemov@linux.intel.com> <1381428359-14843-35-git-send-email-kirill.shutemov@linux.intel.com> <00000141a3f48ada-37ee9c14-2f2b-40a2-93f4-70258363351b-000000@email.amazonses.com> <20131010200921.91D84E0090@blue.fi.intel.com> <00000141a7d2aa7b-e59f292a-746c-4f55-aa51-9fa060a7fbeb-000000@email.amazonses.com> <20131014090437.F22CBE0090@blue.fi.intel.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-SES-Outgoing: 2013.10.14-54.240.9.50 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 916 Lines: 22 On Mon, 14 Oct 2013, Kirill A. Shutemov wrote: > > > > Could you make the check a CONFIG option? CONFIG_PTLOCK_DOES_NOT_FIT_IN_PAGE_STRUCT or > > > > so? > > > > > > No. We will have to track what affects sizeof(spinlock_t) manually. > > > Not a fun and error prune. > > > > You can generate a config option depending on the size of the object via > > Kbuild. Kbuild will determine the setting before building the kernel as a > > whole by runing some small C program. > > I don't think it's any better than what we have there now. Well with the CONFIG options we can then create macros etc that handle things differently depending on the ptl being in the page or not. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/