From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932194Ab3KFLTK (ORCPT ); Wed, 6 Nov 2013 06:19:10 -0500 Received: from merlin.infradead.org ([205.233.59.134]:52257 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932151Ab3KFLTG (ORCPT ); Wed, 6 Nov 2013 06:19:06 -0500 Date: Wed, 6 Nov 2013 12:18:45 +0100 From: Peter Zijlstra To: "Kirill A. Shutemov" Cc: Andrew Morton , "Kirill A. Shutemov" , Ingo Molnar , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org Subject: Re: [PATCH] mm: create a separate slab for page->ptl allocation Message-ID: <20131106111845.GG26785@twins.programming.kicks-ass.net> 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> <20131106093131.GU28601@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131106093131.GU28601@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 06, 2013 at 10:31:31AM +0100, Peter Zijlstra wrote: > Subject: mm: Properly separate the bloated ptl from the regular case > > Use kernel/bounds.c to convert build-time spinlock_t size into a > preprocessor symbol and apply that to properly separate the page::ptl > situation. > > Signed-off-by: Peter Zijlstra > --- > include/linux/mm.h | 24 +++++++++++++----------- > include/linux/mm_types.h | 9 +++++---- > kernel/bounds.c | 2 ++ > mm/memory.c | 11 +++++------ > 4 files changed, 25 insertions(+), 21 deletions(-) > > diff --git a/kernel/bounds.c b/kernel/bounds.c > index e8ca97b5c386..5982437eca2c 100644 > --- a/kernel/bounds.c > +++ b/kernel/bounds.c > @@ -11,6 +11,7 @@ > #include > #include > #include > +#include > > void foo(void) > { > @@ -21,5 +22,6 @@ void foo(void) > #ifdef CONFIG_SMP > DEFINE(NR_CPUS_BITS, ilog2(CONFIG_NR_CPUS)); > #endif > + DEFINE(BLOATED_SPINLOCKS, sizeof(spinlock_t) > sizeof(int)); > /* End of constants */ > } Using that we could also do.. not been near a compiler. --- Subject: lockref: Use bloated_spinlocks to avoid explicit config dependencies Avoid the fragile Kconfig construct guestimating spinlock_t sizes; use a friendly compile-time test to determine this. Not-Signed-off-by: Peter Zijlstra --- lib/Kconfig | 3 --- lib/lockref.c | 2 +- 2 files changed, 1 insertion(+), 4 deletions(-) diff --git a/lib/Kconfig b/lib/Kconfig index b3c8be0da17f..254af289d1d0 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -54,9 +54,6 @@ config ARCH_USE_CMPXCHG_LOCKREF config CMPXCHG_LOCKREF def_bool y if ARCH_USE_CMPXCHG_LOCKREF depends on SMP - depends on !GENERIC_LOCKBREAK - depends on !DEBUG_SPINLOCK - depends on !DEBUG_LOCK_ALLOC config CRC_CCITT tristate "CRC-CCITT functions" diff --git a/lib/lockref.c b/lib/lockref.c index 6f9d434c1521..a158fd86aa1a 100644 --- a/lib/lockref.c +++ b/lib/lockref.c @@ -1,7 +1,7 @@ #include #include -#ifdef CONFIG_CMPXCHG_LOCKREF +#if defined(CONFIG_CMPXCHG_LOCKREF) && !BLOATED_SPINLOCKS /* * Allow weakly-ordered memory architectures to provide barrier-less