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McKenney" , Steven Rostedt , Masami Hiramatsu , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Paolo Bonzini , Wanpeng Li , Vitaly Kuznetsov , Andy Lutomirski , Peter Zijlstra , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Andrew Morton , Uladzislau Rezki , Christoph Hellwig , Lorenzo Stoakes , Josh Poimboeuf , Jason Baron , Kees Cook , Sami Tolvanen , Ard Biesheuvel , Nicholas Piggin , Juerg Haefliger , Nicolas Saenz Julienne , "Kirill A. Shutemov" , Nadav Amit , Dan Carpenter , Chuang Wang , Yang Jihong , Petr Mladek , "Jason A. Donenfeld" , Song Liu , Julian Pidancet , Tom Lendacky , Dionna Glaze , Thomas =?utf-8?Q?Wei=C3=9Fschuh?= , Juri Lelli , Daniel Bristot de Oliveira , Marcelo Tosatti , Yair Podemsky Subject: Re: [RFC PATCH v2 16/20] rcu: Make RCU dynticks counter size configurable In-Reply-To: <20230720163056.2564824-17-vschneid@redhat.com> References: <20230720163056.2564824-1-vschneid@redhat.com> <20230720163056.2564824-17-vschneid@redhat.com> Date: Fri, 21 Jul 2023 09:17:53 +0100 Message-ID: MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Rspamd-Queue-Id: 24392C0013 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: mj1ej7a7affxtm16u1k9w6iibog6e99k X-HE-Tag: 1689927479-4565 X-HE-Meta: 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 ou4Lpx48 mrSPs4WSrNENkZTsgAywVU98CV3UfZ44gA/pQhISEJLSv45N4dci6HQTdjExVZdPb1U3kcjUd27H61b99EAE1VXOI1fxDf8cNJe8Ir2lI2hI3PXb6i93dvEjW2RKeevTJQKmqNghKFvTZdXl3/4qKbOGMgddFyUI5o+/y2B5QkASaSehcI7daHycx4HfLVhi5unvOjpkLnBdqku0d0Hv2rl9MOiGDXQZWcFeQWsavxD20fYvrcQN1yMJe1EE+CzC5CibqKtBHLCoOCt3Od6N/9iwGRYZlAkfWoFKksJws0Ky1XeUkPY7UiGTzymf2zH3pKOHL0ktmb/zsPidBF89Z7K/MUw== 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: On 20/07/23 17:30, Valentin Schneider wrote: > index bdd7eadb33d8f..1ff2aab24e964 100644 > --- a/kernel/rcu/Kconfig > +++ b/kernel/rcu/Kconfig > @@ -332,4 +332,37 @@ config RCU_DOUBLE_CHECK_CB_TIME > Say Y here if you need tighter callback-limit enforcement. > Say N here if you are unsure. > > +config RCU_DYNTICKS_RANGE_BEGIN > + int > + depends on !RCU_EXPERT > + default 31 if !CONTEXT_TRACKING_WORK You'll note that this should be 30 really, because the lower *2* bits are taken by the context state (CONTEXT_GUEST has a value of 3). This highlights the fragile part of this: the Kconfig values are hardcoded, but they depend on CT_STATE_SIZE, CONTEXT_MASK and CONTEXT_WORK_MAX. The static_assert() will at least capture any misconfiguration, but having that enforced by the actual Kconfig ranges would be less awkward. Do we currently have a way of e.g. making a Kconfig file depend on and use values generated by a C header?