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AJvYcCWaGUHSvV6aPdmZwSy5evUKLSvvxWp6S/xqNKOgWumvPho/MkayjTJu7njSREcomrrmXyUh6JB4rXhtlUYbG25642Q= X-Gm-Message-State: AOJu0YzKnvosWoeKMamdvALqms6pLKmbcAXKUI8QBcMQfQuhRf44Qd1O zQdCa2+r/PuUCwXxGwpXM/5MUpep+kXqpFRdDwzhijSeCw+pvMUwZpwBtzImZ+EZHJHPIkdseIo 3yuuVLSgDni6my4rdjW/bTx+xBZKeUWnGx9Rccg== X-Google-Smtp-Source: AGHT+IEboSl6cuP7DdeifGdtYnGd5qh7/n6H6xuvUtUtKpoRuNfSrEar8wpjtJrO/8OKTRTzH9jgVk6mIIwRg3sA+rc= X-Received: by 2002:ac8:5aca:0:b0:441:37b:cd5e with SMTP id d75a77b69052e-4415abc6032mr37434341cf.5.1718214837393; Wed, 12 Jun 2024 10:53:57 -0700 (PDT) MIME-Version: 1.0 References: <20240605222751.1406125-1-souravpanda@google.com> <20240611153003.9f1b701e0ed28b129325128a@linux-foundation.org> In-Reply-To: <20240611153003.9f1b701e0ed28b129325128a@linux-foundation.org> From: Pasha Tatashin Date: Wed, 12 Jun 2024 13:53:20 -0400 Message-ID: Subject: Re: [PATCH v13] mm: report per-page metadata information To: Andrew Morton Cc: Sourav Panda , corbet@lwn.net, gregkh@linuxfoundation.org, rafael@kernel.org, mike.kravetz@oracle.com, muchun.song@linux.dev, rppt@kernel.org, david@redhat.com, rdunlap@infradead.org, chenlinxuan@uniontech.com, yang.yang29@zte.com.cn, tomas.mudrunka@gmail.com, bhelgaas@google.com, ivan@cloudflare.com, yosryahmed@google.com, hannes@cmpxchg.org, shakeelb@google.com, kirill.shutemov@linux.intel.com, wangkefeng.wang@huawei.com, adobriyan@gmail.com, vbabka@suse.cz, Liam.Howlett@oracle.com, surenb@google.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, willy@infradead.org, weixugc@google.com, David Rientjes Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 7588F140015 X-Rspamd-Server: rspam10 X-Rspam-User: X-Stat-Signature: o3sf9nff7578f1tokk8whczy9nz544tn X-HE-Tag: 1718214838-968527 X-HE-Meta: U2FsdGVkX19orV8zUILnofl5Qnl+WVSwXuUIx0JsdYF3zPOsi1DXlhg9nJen5EjBqDZB2CtFMQiZet3ZTOq9h60TcmYbSw+fL6aQ1Abvvzf3SLfc94R47m7QETnqJ8bXU8ElkvOAs9Esy8yq1dSTI5/4OJE/eCgrEki/0DnxMFu4B0tvCLrhxCKL3ZGALM0QT0KYZDrSgEgBgi9lB9WzIUU67ztSThcQmUgUDpayc3bStDh8vy0g7w7zr4bcT6W8xnRkUPcsiXm/rDxa1PYPVyTJ4sfR/9HZ0fgiTEdtDqSugbRd867JXizicem9gV5AASJ0VfJwhZ8lA0GSNwNtWElG80vVEuf0aLd8FDAl5Om0FYl95HJNg2nxbCLXLtAnUh1BupsQylbVCJDveG50qqPoI7ZaoygWGcTkX0ajobvH4nSIelwgW0f1yqX3DU9RLzKiVaq2Ibfbf2lHHvx7PQcDtq0z6HKgjA91VNeSX8UkG/Z3PlrhdXA6QxiZVRS2KMDXrI0xX+4mFtgCP9zKR0spOtfiDM3a4oVt9bbsCxfrDlXcapEc/KH5fEb2w0ZFeZDDRhMc7vJXwWp9z6lyRvVxZVfBcag+qvEJaxvy/rdycJEJO+dJXxR/SzUf9yh3TomfPPxPXy79LCMfqIrhhbK8OVrVswHllXTvY0nc5hgpCjiOC6q55Mw9KdDOwqf5uiNPbVAEhMg1+bzw8H3pwoxKRuuJ1bkjAexv3risjRs83erK4IYEeZa3aV1QJBNA+fCSO8tg/sdnaAQ5rv0vc+03EuDNL4lzxYeTu/7d7DgJtchQNdOJEvdAl3kt8Fw01jOPAxQzADARHRI8jlpp+Kg3NV7BiqScHa1WcoqqioSCY2oBRPRgBNZlDzRlz5GHeg4u41zv672+GL9/Cg9CCOVmngXp95cmpo6e42CosJ4VH4/M+qDes6BDHHRgl9Qt/eKucGHcYjIp/mDIBUL qev3RjdD tQl6e+cofveLc1rYyJNsksl4MZFYsm4nGLuM3COBhdHwvralyCVVG54lrLbLIKySd9fi3Ea6iij91Crz9igqfZ1imxJZwMQCwkAw2PCqOHU87GACOQ8fvRJIGkCFIaithsl7HK+STXW1BcWOyVRgh/SIO6lPBtcqtkH4OLtLcxPdW6oWUSqDoBY0jn2RRsb2uJw7NMc7+H5kysQptu65/sN57aKsyIdngDdogmT1fsaW9A0b4NKaMAldGgyFwbmlBHq0EFXVnXkKMQR+f9cDl/6GZXOAjnO2vMnjxlQVcaytckkYTnm6VlFC7xBOjEnczEYzGo3fuXdd/nuXBjbX0TrJrcxM0yAJeambv 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: On Tue, Jun 11, 2024 at 6:30=E2=80=AFPM Andrew Morton wrote: > > On Wed, 5 Jun 2024 22:27:51 +0000 Sourav Panda = wrote: > > > Today, we do not have any observability of per-page metadata > > and how much it takes away from the machine capacity. Thus, > > we want to describe the amount of memory that is going towards > > per-page metadata, which can vary depending on build > > configuration, machine architecture, and system use. > > > > This patch adds 2 fields to /proc/vmstat that can used as shown > > below: > > > > Accounting per-page metadata allocated by boot-allocator: > > /proc/vmstat:nr_memmap_boot * PAGE_SIZE > > > > Accounting per-page metadata allocated by buddy-allocator: > > /proc/vmstat:nr_memmap * PAGE_SIZE > > > > Accounting total Perpage metadata allocated on the machine: > > (/proc/vmstat:nr_memmap_boot + > > /proc/vmstat:nr_memmap) * PAGE_SIZE > > Under what circumstances do these change? Only hotplug? Currently, there are several reasons these numbers can change during runtim= e: 1. Memory hotplug/hotremove 2. Adding/Removing hugetlb pages with vmemmap optimization 3. Adding/Removing Device DAX with vmemmap optimization. > > It's nasty, but would it be sufficient to simply emit these numbers > into dmesg when they change? These numbers should really be part of /proc/vmstat in order to provide an interface for determining the system memory overhead. Pasha