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Shenoy" , Richard Henderson , Ivan Kokshaysky , Matt Turner , Russell King , "Guo Ren" , Michal Simek , Dinh Nguyen , Jonas Bonn , Stefan Kristiansson , Stafford Horne , "James E.J. Bottomley" , Helge Deller , Michael Ellerman , Nicholas Piggin , Christophe Leroy , "Aneesh Kumar K.V" , "Naveen N. Rao" , Yoshinori Sato , Rich Felker , John Paul Adrian Glaubitz , "David S. Miller" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , "Rafael J. Wysocki" , Daniel Lezcano , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , "Mel Gorman" , Daniel Bristot de Oliveira , Valentin Schneider , Al Viro , Linus Walleij , Ard Biesheuvel , Andrew Donnellan , Nicholas Miehlbradt , Andrew Morton , "Arnd Bergmann" , Josh Poimboeuf , "Kirill A. Shutemov" , Rick Edgecombe , Tony Battersby , "Brian Gerst" , Tim Chen , "David Vernet" , , , , , , , , , , , K Prateek Nayak Subject: [RFC PATCH 01/14] thread_info: Add helpers to test and clear TIF_NOTIFY_IPI Date: Tue, 20 Feb 2024 22:44:44 +0530 Message-ID: <20240220171457.703-2-kprateek.nayak@amd.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240220171457.703-1-kprateek.nayak@amd.com> References: <20240220171457.703-1-kprateek.nayak@amd.com> Precedence: bulk X-Mailing-List: linux-parisc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: SATLEXMB04.amd.com (10.181.40.145) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS1PEPF00017095:EE_|DM6PR12MB4203:EE_ X-MS-Office365-Filtering-Correlation-Id: 4eb4d987-a812-4cdb-a2a9-08dc3237a66d X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:SATLEXMB04.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230031)(36860700004)(40470700004)(46966006);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Feb 2024 17:16:17.5310 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 4eb4d987-a812-4cdb-a2a9-08dc3237a66d X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: DS1PEPF00017095.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR12MB4203 From: "Gautham R. Shenoy" Introduce the notion of TIF_NOTIFY_IPI flag. When a processor in TIF_POLLING mode needs to process an IPI, the sender sets NEED_RESCHED bit in idle task's thread_info to pull the target out of idle and avoids sending an interrupt to the idle CPU. When NEED_RESCHED is set, the scheduler assumes that a new task has been queued on the idle CPU and calls schedule_idle(), however, it is not necessary that an IPI on an idle CPU will necessarily end up waking a task on the said CPU. To avoid spurious calls to schedule_idle() assuming an IPI on an idle CPU will always wake a task on the said CPU, TIF_NOTIFY_IPI will be used to pull a TIF_POLLING CPU out of idle. Since the IPI handlers are processed before the call to schedule_idle(), schedule_idle() will be called only if one of the handlers have woken up a new task on the CPU and has set NEED_RESCHED. Add tif_notify_ipi() and current_clr_notify_ipi() helpers to test if TIF_NOTIFY_IPI is set in the current task's thread_info, and to clear it respectively. These interfaces will be used in subsequent patches as TIF_NOTIFY_IPI notion is integrated in the scheduler and in the idle path. [ prateek: Split the changes into a separate patch, add commit log ] Cc: Richard Henderson Cc: Ivan Kokshaysky Cc: Matt Turner Cc: Russell King Cc: Guo Ren Cc: Michal Simek Cc: Dinh Nguyen Cc: Jonas Bonn Cc: Stefan Kristiansson Cc: Stafford Horne Cc: "James E.J. Bottomley" Cc: Helge Deller Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Christophe Leroy Cc: "Aneesh Kumar K.V" Cc: "Naveen N. Rao" Cc: Yoshinori Sato Cc: Rich Felker Cc: John Paul Adrian Glaubitz Cc: "David S. Miller" Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: "H. Peter Anvin" Cc: "Rafael J. Wysocki" Cc: Daniel Lezcano Cc: Peter Zijlstra Cc: Juri Lelli Cc: Vincent Guittot Cc: Dietmar Eggemann Cc: Steven Rostedt Cc: Ben Segall Cc: Mel Gorman Cc: Daniel Bristot de Oliveira Cc: Valentin Schneider Cc: Al Viro Cc: Linus Walleij Cc: Ard Biesheuvel Cc: Andrew Donnellan Cc: Nicholas Miehlbradt Cc: Andrew Morton Cc: Arnd Bergmann Cc: Josh Poimboeuf Cc: "Kirill A. Shutemov" Cc: Rick Edgecombe Cc: Tony Battersby Cc: Brian Gerst Cc: Tim Chen Cc: David Vernet Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-alpha@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-csky@vger.kernel.org Cc: linux-openrisc@vger.kernel.org Cc: linux-parisc@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-sh@vger.kernel.org Cc: sparclinux@vger.kernel.org Cc: linux-pm@vger.kernel.org Signed-off-by: Gautham R. Shenoy Co-developed-by: K Prateek Nayak Signed-off-by: K Prateek Nayak --- include/linux/thread_info.h | 43 +++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h index 9ea0b28068f4..1e10dd8c0227 100644 --- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -195,6 +195,49 @@ static __always_inline bool tif_need_resched(void) #endif /* _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H */ +#ifdef TIF_NOTIFY_IPI + +#ifdef _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H + +static __always_inline bool tif_notify_ipi(void) +{ + return arch_test_bit(TIF_NOTIFY_IPI, + (unsigned long *)(¤t_thread_info()->flags)); +} + +static __always_inline void current_clr_notify_ipi(void) +{ + arch_clear_bit(TIF_NOTIFY_IPI, + (unsigned long *)(¤t_thread_info()->flags)); +} + +#else + +static __always_inline bool tif_notify_ipi(void) +{ + return test_bit(TIF_NOTIFY_IPI, + (unsigned long *)(¤t_thread_info()->flags)); +} + +static __always_inline void current_clr_notify_ipi(void) +{ + clear_bit(TIF_NOTIFY_IPI, + (unsigned long *)(¤t_thread_info()->flags)); +} + +#endif /* _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H */ + +#else /* !TIF_NOTIFY_IPI */ + +static __always_inline bool tif_notify_ipi(void) +{ + return false; +} + +static __always_inline void current_clr_notify_ipi(void) { } + +#endif /* TIF_NOTIFY_IPI */ + #ifndef CONFIG_HAVE_ARCH_WITHIN_STACK_FRAMES static inline int arch_within_stack_frames(const void * const stack, const void * const stackend,