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(p200300cbc702dc002571c3c2c6ea84ef.dip0.t-ipconnect.de. [2003:cb:c702:dc00:2571:c3c2:c6ea:84ef]) by smtp.gmail.com with ESMTPSA id l24-20020a05600c1d1800b003cf878c4468sm19240074wms.5.2022.11.21.00.00.59 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 21 Nov 2022 00:01:01 -0800 (PST) Message-ID: <7b2055f2-f5ce-be01-7c39-edcc4be6a7aa@redhat.com> Date: Mon, 21 Nov 2022 09:00:59 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.1 To: kernel test robot Cc: oe-lkp@lists.linux.dev, lkp@intel.com, Andrew Morton , Jason Gunthorpe , John Hubbard , Andrea Arcangeli , Hugh Dickins , Peter Xu , Alistair Popple , Nadav Amit , Yang Shi , Vlastimil Babka , Michal Hocko , Mike Kravetz , Andrea Parri , Will Deacon , Peter Zijlstra , "Paul E. McKenney" , Christoph von Recklinghausen , Don Dutile , linux-kernel@vger.kernel.org, linux-mm@kvack.org, ying.huang@intel.com, feng.tang@intel.com, zhengjun.xing@linux.intel.com, fengwei.yin@intel.com References: <202211211037.2b2e5e1f-yujie.liu@intel.com> Content-Language: en-US From: David Hildenbrand Organization: Red Hat Subject: Re: [linus:master] [mm] 088b8aa537: vm-scalability.throughput -6.5% regression In-Reply-To: <202211211037.2b2e5e1f-yujie.liu@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 21.11.22 04:03, kernel test robot wrote: > Greeting, > > FYI, we noticed a -6.5% regression of vm-scalability.throughput due to commit: > > commit: 088b8aa537c2c767765f1c19b555f21ffe555786 ("mm: fix PageAnonExclusive clearing racing with concurrent RCU GUP-fast") > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master > > in testcase: vm-scalability > on test machine: 88 threads 2 sockets Intel(R) Xeon(R) Gold 6238M CPU @ 2.10GHz (Cascade Lake) with 128G memory > with following parameters: > > thp_enabled: never > thp_defrag: never > nr_task: 1 > nr_pmem: 2 > priority: 1 > test: swap-w-seq > cpufreq_governor: performance > > test-description: The motivation behind this suite is to exercise functions and regions of the mm/ of the Linux kernel which are of interest to us. > test-url: https://git.kernel.org/cgit/linux/kernel/git/wfg/vm-scalability.git/ > Yes, page_try_share_anon_rmap() might now be a bit more expensive now, turning try_to_unmap_one() a bit more expensive. However, that patch also changes the unconditional TLB flush into a conditional TLB flush, so results might vary heavily between machines/architectures. smp_mb__after_atomic() is a NOP on x86, so the smp_mb() before the page_maybe_dma_pinned() check would have to be responsible. While there might certainly be ways for optimizing that further (e.g., if the ptep_get_and_clear() already implies a smp_mb()), the facts that: (1) It's a swap micro-benchmark (2) We have 3% stddev Don't make me get active now ;) -- Thanks, David / dhildenb