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b=T3RJ+eD3P4krbidA4Ux+D5n2CGZ52JX4U90QOuKkNuirMUx4ftzcL9Zq24mhdBYEk ic3BoOiWj/dNwNV89puB3YidkIcSOC7UcAU9JGdkmdzgU7pUYfZEzh8PX0cgRUw4lj 0o0Zw1EDkU0R4rYRwSe9Cad/EHVH6N0WhkKnN1HUVRyaCcZinvkHrvemcLzdsn4nvm 2fQythfK+JGXpeCwVuW6wNxQ04MsxSNmJQgPRhIkokdjTqhUBHHVqtoclNUI5Ax9Y5 B2T9wcrvandZRpNJnooCKA0KPITePq8Ae89YJI67TVPOWU1j5QOKn5GCL6cabvx0CL m0FQi7LDFyd1A== Date: Sat, 4 May 2024 13:24:23 +0200 From: Christian Brauner To: Andrii Nakryiko Cc: linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, gregkh@linuxfoundation.org, linux-mm@kvack.org Subject: Re: [PATCH 0/5] ioctl()-based API to query VMAs from /proc//maps Message-ID: <20240504-rasch-gekrochen-3d577084beda@brauner> References: <20240504003006.3303334-1-andrii@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240504003006.3303334-1-andrii@kernel.org> X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 738C040012 X-Stat-Signature: dn15dpenh5rphhuw6kdid39fxm6u5y1m X-HE-Tag: 1714821874-531459 X-HE-Meta: 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 rO+6bWZ/ uE2S8Fl+nwMslfqTkHbrfwg2dq4ELMORsOHkxVL/3NEltp5x6fACakqXHcoG1BO7Hg/1OecLYmykL159zHhEzvqtbi/oSBhD+tY2KgasoWiXd5Bv3R5S7Le898q2uZ8gn5q0NcJbEgkPoYrw4lBwteaSVKQFVp9ill7pxewF/0DqXMihZLyfiv+BRwA== 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 Fri, May 03, 2024 at 05:30:01PM -0700, Andrii Nakryiko wrote: > Implement binary ioctl()-based interface to /proc//maps file to allow > applications to query VMA information more efficiently than through textual > processing of /proc//maps contents. See patch #2 for the context, > justification, and nuances of the API design. > > Patch #1 is a refactoring to keep VMA name logic determination in one place. > Patch #2 is the meat of kernel-side API. > Patch #3 just syncs UAPI header (linux/fs.h) into tools/include. > Patch #4 adjusts BPF selftests logic that currently parses /proc//maps to > optionally use this new ioctl()-based API, if supported. > Patch #5 implements a simple C tool to demonstrate intended efficient use (for > both textual and binary interfaces) and allows benchmarking them. Patch itself > also has performance numbers of a test based on one of the medium-sized > internal applications taken from production. I don't have anything against adding a binary interface for this. But it's somewhat odd to do ioctls based on /proc files. I wonder if there isn't a more suitable place for this. prctl()? New vmstat() system call using a pidfd/pid as reference? ioctl() on fs/pidfs.c?