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Thu, 03 Oct 2019 01:36:04 +0000 Received: from b03ledav004.gho.boulder.ibm.com (b03ledav004.gho.boulder.ibm.com [9.17.130.235]) by b03cxnp08028.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x931a2MW66126324 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 3 Oct 2019 01:36:02 GMT Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3CAB578060; Thu, 3 Oct 2019 01:36:02 +0000 (GMT) Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C03DC7805E; Thu, 3 Oct 2019 01:35:49 +0000 (GMT) Received: from LeoBras.ibmuc.com (unknown [9.85.174.224]) by b03ledav004.gho.boulder.ibm.com (Postfix) with ESMTP; Thu, 3 Oct 2019 01:35:49 +0000 (GMT) From: Leonardo Bras 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: Leonardo Bras , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Arnd Bergmann , "Aneesh Kumar K.V" , Christophe Leroy , Nicholas Piggin , Andrew Morton , Mahesh Salgaonkar , Reza Arbab , Santosh Sivaraj , Balbir Singh , Thomas Gleixner , Greg Kroah-Hartman , Mike Rapoport , Allison Randal , Jason Gunthorpe , Dan Williams , Vlastimil Babka , Christoph Lameter , Logan Gunthorpe , Andrey Ryabinin , Alexey Dobriyan , Souptick Joarder , Mathieu Desnoyers , Ralph Campbell , Jesper Dangaard Brouer , Jann Horn , Davidlohr Bueso , "Peter Zijlstra (Intel)" , Ingo Molnar , Christian Brauner , Michal Hocko , Elena Reshetova , Roman Gushchin , Andrea Arcangeli , Al Viro , "Dmitry V. Levin" , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Song Liu , Bartlomiej Zolnierkiewicz , Ira Weiny , "Kirill A. Shutemov" , John Hubbard , Keith Busch 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> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191003013325.2614-1-leonardo@linux.ibm.com> References: <20191003013325.2614-1-leonardo@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-10-03_01:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=974 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1910030012 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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