From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH] mm: create a separate slab for page->ptl allocation Date: Tue, 5 Nov 2013 16:43:51 -0800 Message-ID: <20131105164351.b2c63109.akpm@linux-foundation.org> References: <1382442839-7458-1-git-send-email-kirill.shutemov@linux.intel.com> <20131105150145.734a5dd5b5d455800ebfa0d3@linux-foundation.org> <20131105224217.GC20167@shutemov.name> <20131105155619.021f32eba1ca8f15a73ed4c9@linux-foundation.org> <20131105231310.GE20167@shutemov.name> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from mail.linuxfoundation.org ([140.211.169.12]:59668 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755558Ab3KFAmS (ORCPT ); Tue, 5 Nov 2013 19:42:18 -0500 In-Reply-To: <20131105231310.GE20167@shutemov.name> Sender: linux-arch-owner@vger.kernel.org List-ID: To: "Kirill A. Shutemov" Cc: "Kirill A. Shutemov" , Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org On Wed, 6 Nov 2013 01:13:11 +0200 "Kirill A. Shutemov" wrote: > > Really the function shouldn't exist in this case. It is __init so the > > sin is not terrible, but can this be arranged? > > I would like to get rid of __ptlock_alloc()/__ptlock_free() too, but I > don't see a way within C: we need to know sizeof(spinlock_t) on > preprocessor stage. > > We can have a hack on kbuild level: write small helper program to find out > sizeof(spinlock_t) before start building and turn it into define. > But it's overkill from my POV. And cross-compilation will be a fun. Yes, it doesn't seem worth the fuss. The compiler will remove all this code anyway, so for example ptlock_cache_init() becomes an empty function.