From mboxrd@z Thu Jan 1 00:00:00 1970 From: Leonardo Bras Subject: [PATCH v5 10/11] mm/Kconfig: Adds config option to track lockless pagetable walks Date: Wed, 2 Oct 2019 22:33:24 -0300 Message-ID: <20191003013325.2614-11-leonardo@linux.ibm.com> References: <20191003013325.2614-1-leonardo@linux.ibm.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20191003013325.2614-1-leonardo@linux.ibm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+glppe-linuxppc-embedded-2=m.gmane.org@lists.ozlabs.org Sender: "Linuxppc-dev" To: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org Cc: Song Liu , Michal Hocko , "Peter Zijlstra (Intel)" , "Dmitry V. Levin" , Keith Busch , Paul Mackerras , Christoph Lameter , Ira Weiny , Thomas Gleixner , Elena Reshetova , Andrea Arcangeli , Santosh Sivaraj , Davidlohr Bueso , "Aneesh Kumar K.V" , Bartlomiej Zolnierkiewicz , Mike Rapoport , Jason Gunthorpe , Allison Randal , Mahesh Salgaonkar , Leonardo Bras , Alexey Dobriyan , Ingo Molnar , Ralph Campbell List-Id: linux-arch.vger.kernel.org Adds config option LOCKLESS_PAGE_TABLE_WALK_TRACKING to make possible enabling tracking lockless pagetable walks directly from kernel config. Signed-off-by: Leonardo Bras --- mm/Kconfig | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/mm/Kconfig b/mm/Kconfig index a5dae9a7eb51..00f487a0122f 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -736,4 +736,15 @@ config ARCH_HAS_PTE_SPECIAL config ARCH_HAS_HUGEPD bool +config LOCKLESS_PAGE_TABLE_WALK_TRACKING + bool "Track (and optimize) lockless page table walks" + default n + + help + Maintain a reference count of active lockless page table + walkers. This adds 4 bytes to struct mm size, and two atomic + operations to calls such as get_user_pages_fast(). Some + architectures can optimize lockless page table operations if + this is enabled. + endmenu -- 2.20.1