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To: Barret Rhoden Cc: Donald Hunter , bpf , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Kumar Kartikeya Dwivedi , Eddy Z , Tejun Heo , Johannes Weiner , linux-mm , Kernel Team Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 2B9C9100022 X-Stat-Signature: cm56pb3ac764jxk1z68habpxw7aac996 X-Rspam-User: X-HE-Tag: 1707337002-517685 X-HE-Meta: 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 u9eElID4 7h4gFa4E3VghHDmqveJCx5WkhgQ5NXXrfTWMoERb4hQm6S7aqu3zH96+0HoUBBver8UM+7dFg5NWE0ScfemCsPYJiKaaNbJoSzbpyYxbvAIeViuWZp5vs6YwhWAQCVysGEM82E+iZWM+PdCwQVPwa+lVlxfy67QkluVfOhtD9G1YCLUIMazQ1VboPVaFWE5RId3T4hNqJEYCQAqNF/oxX41gKSncglb/XcQEdJg2iW1FWqVln8Yoim/NX6hWWLbdPkTpUh1Jwv1t3Ic8wJoOYD5QJZeteXu15w6XbGilvrC7X29IL4lxjMhfuALFPC2Y/gUG95nd8S71mSB8yCChsjrcoF5vtKr6MWbN8xESkpgGpNzC88AZDGfi4OrLdn5dzga4p7XaYnXgkUfWNESuJIa51p7yOvNJxBqMBbrxq3kQwYq7is+KclamdxEMmPCXM6FhGvYe5ZBdpTUfgpYKDLCMjj3fGJSJGTl3R X-Bogosity: Ham, tests=bogofilter, spamicity=0.053541, 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 Wed, Feb 7, 2024 at 5:33=E2=80=AFAM Barret Rhoden wrot= e: > > > if i knew userspace wasn't going to follow pointers, NO_USER_CONV would > both be a speedup and make it so i don't have to worry about mmapping to > the same virtual address in every process that shares the arena map. > though this latter feature isn't in the code. right now you have to > have it mmapped at the same user_va in all address spaces. that's not a > huge deal for me either way. Not quite. With: struct { __uint(type, BPF_MAP_TYPE_ARENA); ... __ulong(map_extra, 2ull << 44); /* start of mmap() region */ ... } arena SEC(".maps"); the future user_vm_start will be specified at map creation time, so arena doesn't have to be mapped to be usable. But having an address known early helps potential future mmap-s. Like to examine the state of the arena with bpftool.