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Sun, 7 Apr 2024 17:19:07 GMT Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id F2FE620049; Sun, 7 Apr 2024 17:19:04 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C46CC20040; Sun, 7 Apr 2024 17:19:03 +0000 (GMT) Received: from osiris (unknown [9.179.2.159]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTPS; Sun, 7 Apr 2024 17:19:03 +0000 (GMT) Date: Sun, 7 Apr 2024 19:19:02 +0200 From: Heiko Carstens To: Kefeng Wang Cc: Andrew Morton , Russell King , Catalin Marinas , Will Deacon , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexander Gordeev , Gerald Schaefer , Dave Hansen , Andy Lutomirski , Peter Zijlstra , x86@kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, surenb@google.com, linux-mm@kvack.org Subject: Re: [PATCH v2 0/7] arch/mm/fault: accelerate pagefault when badaccess Message-ID: <20240407171902.5958-A-hca@linux.ibm.com> References: <20240403083805.1818160-1-wangkefeng.wang@huawei.com> <20240403134539.fde3a6c594f2d88409be30ed@linux-foundation.org> <4d45fffc-877a-4ad1-ad02-a33341e467e7@huawei.com> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4d45fffc-877a-4ad1-ad02-a33341e467e7@huawei.com> X-TM-AS-GCONF: 00 X-Proofpoint-GUID: Y3MmKFoPZYTA6URYFqSoHvL5OT_14Ypp X-Proofpoint-ORIG-GUID: Ts9vZ863gBFIi5c6rKKJKZ5ZbhTxcstc X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-04-07_11,2024-04-05_02,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 mlxlogscore=950 bulkscore=0 lowpriorityscore=0 priorityscore=1501 mlxscore=0 spamscore=0 impostorscore=0 adultscore=0 clxscore=1011 phishscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2404010000 definitions=main-2404070139 On Sun, Apr 07, 2024 at 03:49:53PM +0800, Kefeng Wang wrote: > On 2024/4/4 4:45, Andrew Morton wrote: > > On Wed, 3 Apr 2024 16:37:58 +0800 Kefeng Wang wrote: > > > > > After VMA lock-based page fault handling enabled, if bad access met > > > under per-vma lock, it will fallback to mmap_lock-based handling, > > > so it leads to unnessary mmap lock and vma find again. A test from > > > lmbench shows 34% improve after this changes on arm64, > > > > > > lat_sig -P 1 prot lat_sig 0.29194 -> 0.19198 > > > > > > Only build test on other archs except arm64. > > > > Thanks. So we now want a bunch of architectures to runtime test this. Do > > we have a selftest in place which will adequately do this? > > I don't find such selftest, and badaccess would lead to coredump, the > performance should not affect most scene, so no selftest is acceptable. > lmbench is easy to use to measure the performance. The rationale for this series (performance improvement) is a bit odd, since I would expect that the changed code is usually never executed.