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Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Sean Christopherson , Paolo Bonzini , Alexandre Chartre , Liran Alon , Jan Setje-Eilers , Catalin Marinas , Will Deacon , Mark Rutland , Andrew Morton , Mel Gorman , Lorenzo Stoakes , David Hildenbrand , Vlastimil Babka , Michal Hocko , Khalid Aziz , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Valentin Schneider , Paul Turner , Reiji Watanabe , Ofir Weisse , Yosry Ahmed , Patrick Bellasi , KP Singh , Alexandra Sandulescu , Matteo Rizzo , Jann Horn , x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kvm@vger.kernel.org Subject: Re: [PATCH 01/26] mm: asi: Make some utility functions noinstr compatible In-Reply-To: References: <20240712-asi-rfc-24-v1-0-144b319a40d8@google.com> <20240712-asi-rfc-24-v1-1-144b319a40d8@google.com> <20241025113455.GMZxuCX2Tzu8ulwN3o@fat_crate.local> Date: Tue, 29 Oct 2024 20:12:59 +0100 Message-ID: <878qu6205g.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 155BC2002A X-Stat-Signature: z6e7nha6sr4tfuo9ta937ncjjzuz6nz9 X-Rspam-User: X-HE-Tag: 1730229170-770935 X-HE-Meta: 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 A11K32bB uFvZJFMBge1scxgxpzCJwEI7Pd2Z2ZMnfFq46qbQJx5sgC8GG9P35KfU+XfZiY5MO9WrlEw2wZA8aMrO6J5zF4XfZoTOSCKUSSLEayTr1ZY+mGaHSfqafk0G7iIb+BFcVmmCIbBYrRIc2TV3R86Rr6+SwGg== 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, Oct 29 2024 at 10:38, Junaid Shahid wrote: > On 10/25/24 6:21 AM, Brendan Jackman wrote: >>> I'd expect you either always inline the small functions - as you do for some >>> aleady - or mark the others noinstr. But not something in between. >>> >>> Why this? >> >> Overall it's pretty likely I'm wrong about the subtlety of noinstr's >> meaning. And the benefits I listed above are pretty minor. I should >> have looked into this as it would have been an opportunity to reduce >> the patch count of this RFC! >> >> Maybe I'm also forgetting something more important, perhaps Junaid >> will weigh in... > > Yes, IIRC the idea was that there is no need to prohibit inlining for this class > of functions. I doubt that it works as you want it to work. + inline notrace __attribute((__section__(".noinstr.text"))) \ So this explicitely puts the inline into the .noinstr.text section, which means when it is used in .text the compiler will generate an out-of line function in the .noinstr.text section and insert a call into the usage site. That's independent of the size of the inline. Thanks, tglx