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AJvYcCVJwRis6axrQyBkMbRkuZhpuc2mKImSpLckSuEHLKhl/fQw+8ZmUIdjS6royHskhHGyOUgNXrO4LQ==@kvack.org X-Gm-Message-State: AOJu0YzDji9eH+SE3alG9N4x8o+uWeqqAk006zsMpiEQLaBlEHaU0z+G DjLmmYsoorJQo6HbhzXAZFQNLMxUkaukNqMwDW81PFJU7VjAPQwkgx8gJIKBlrC7aQYMfIDfsug cPc68m6fWOTHLoc0+p+6+Rtv1MkGQyoA= X-Gm-Gg: ASbGncuPt8zNlRhMjMC5s9wT2JW4IUdT0LF2jZXtG3lasCVaWO+LvlH9tCKlfNrKz+6 KzCQPs1bjwbU6RF6dfdIIVnqptr++LzBiRhTA8OdKZIccOLeMYm6a6dcpaA1DIfKCtvpI0RdWJP OG9TZjQr7pq9hpnq/KKPUiJX6Oq6Sb7A3MiQj51dKFoylV0wqI9Ekah5j5dujEJ/5HjlrwUQqgO fSPME3bFyVgs+qLpfZV19ixqai6s+zlHtg+OMm8OyzJbh+d2qMFEQizADmKKxQEiG5xEI2lYnnE tBabA0l1lNjxMk4l X-Google-Smtp-Source: AGHT+IFTcAOtXGOZhl7XZO47Jw5as7yHXv1okWMKdwokC78k4R5PlQjBIcNv/sxneXQntHqjozJlsExm4jwJsJf+GKs= X-Received: by 2002:a05:620a:2990:b0:82e:ce61:f840 with SMTP id af79cd13be357-89070fc102bmr2871005985a.84.1761197991234; Wed, 22 Oct 2025 22:39:51 -0700 (PDT) MIME-Version: 1.0 References: <20251013092038.6963-1-ying.huang@linux.alibaba.com> <20251013092038.6963-3-ying.huang@linux.alibaba.com> <87a51jfl44.fsf@DESKTOP-5N7EMDA> <871pmv9unr.fsf@DESKTOP-5N7EMDA> <875xc78es0.fsf@DESKTOP-5N7EMDA> <87a51j6zg7.fsf@DESKTOP-5N7EMDA> <87ms5j4444.fsf@DESKTOP-5N7EMDA> <87qzuu1kg2.fsf@DESKTOP-5N7EMDA> In-Reply-To: <87qzuu1kg2.fsf@DESKTOP-5N7EMDA> From: Barry Song <21cnbao@gmail.com> Date: Thu, 23 Oct 2025 18:39:39 +1300 X-Gm-Features: AS18NWDKv8WT7U0pZbWb-8Jorrgh3QZSKh6u4PKNw3UoBHBCpCMmg3gw3nK3q9o Message-ID: Subject: Re: [PATCH -v2 2/2] arm64, tlbflush: don't TLBI broadcast if page reused in write fault To: "Huang, Ying" Cc: Catalin Marinas , Will Deacon , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Vlastimil Babka , Zi Yan , Baolin Wang , Ryan Roberts , Yang Shi , "Christoph Lameter (Ampere)" , Dev Jain , Anshuman Khandual , Yicong Yang , Kefeng Wang , Kevin Brodsky , Yin Fengwei , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: q67bs6krkjkorz9eeh6khorxzxow18my X-Rspamd-Queue-Id: 73365140006 X-Rspamd-Server: rspam06 X-Rspam-User: X-HE-Tag: 1761197992-522408 X-HE-Meta: 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 sAsd5HeH nVKhwYuL7jOcivkJonXnK5IW7bYVBeCyVND42vhypyFEMxLvsaEroWa9CQxZ9fxzjDlTkr77e+uY3/PibgFx2r78BXlFgiaM0hH1Fe5EAyiBqsGVvr2LkqmsfHHk/V0M+rWII94hOsLxMqWsSVwiVedEFYzok40iv4b/HOZIRzih6RN92cNDjXw2kbbmO32AeDP7KKle2LwawqglKg0XY3DL9MFcpCMQNUqOFGe4XsdOey8VWjr0tT+D8jWut2PVgi2NA3FHSsvBJidDQKKU0/equQXEqcDnR3g0XX9SornrgvnrSoNkQs2mWvKeDJzF/zPoDJzBCG74SrAZmX0JI+eySSrAssPmJ2eY9 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: List-Subscribe: List-Unsubscribe: > > > > A: > > write pte > > don't broadcast pte > > tlbi > > don't broadcast tlbi > > > > with > > > > B: > > write pte > > broadcast pte > > I suspect that pte will be broadcast, DVM broadcast isn't used for > the memory coherency IIUC. I guess you=E2=80=99re right. By =E2=80=9Cbroadcast,=E2=80=9D I actually me= ant the PTE becoming visible to other CPUs. With a dsb(ish) before tlbi, other cores=E2=80=99 TLBs can l= oad the new PTE after their TLB is shoot down. But as you said, if the hardware doesn= =E2=80=99t propagate the updated PTE faster, it doesn=E2=80=99t seem to help reduce pa= ge faults. As a side note, I=E2=80=99m curious about the data between dsb(nsh) and dsb= (ish) on your platform. Perhaps because the number of CPU cores is small, I didn=E2= =80=99t see any noticeable difference between them on phones. > > > tlbi > > don't broadcast tlbi > > > > I guess the gain comes from "don't broadcat tlbi" ? > > With B, we should be able to share many existing code. > > Ryan has some plan to reduce the code duplication with the current > solution. Ok. Thanks Barry