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b=BvMeoq5NM+5uStD8+OZHyGxYpolkcrXJg2jEK1fWVdPDzrMFsPmJHm105nXMhbIIB4mT8kbibvZyUpMAfdVSzz10f4JeegmgiyyI////cAhLoIoLglc1FjIQ/sFkAKQODZWGZ3VwxDpkEEZkLwY3q6PhybqEISzeLBt96Q4jOfY= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from CH3PR12MB8658.namprd12.prod.outlook.com (2603:10b6:610:175::8) by DS4PR12MB9660.namprd12.prod.outlook.com (2603:10b6:8:281::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8880.30; Tue, 1 Jul 2025 03:12:51 +0000 Received: from CH3PR12MB8658.namprd12.prod.outlook.com ([fe80::d5cc:cc84:5e00:2f42]) by CH3PR12MB8658.namprd12.prod.outlook.com ([fe80::d5cc:cc84:5e00:2f42%4]) with mapi id 15.20.8880.027; Tue, 1 Jul 2025 03:12:50 +0000 Message-ID: <953c7749-5c91-40d9-ab1a-bdf82987d256@amd.com> Date: Tue, 1 Jul 2025 08:42:44 +0530 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V6 7/7] Introduce a config option for scheduler time slice extension feature To: Prakash Sangappa , linux-kernel@vger.kernel.org Cc: peterz@infradead.org, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, tglx@linutronix.de, bigeasy@linutronix.de, vineethr@linux.ibm.com References: <20250701003749.50525-1-prakash.sangappa@oracle.com> <20250701003749.50525-8-prakash.sangappa@oracle.com> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <20250701003749.50525-8-prakash.sangappa@oracle.com> Content-Type: text/plain; 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On 7/1/2025 6:07 AM, Prakash Sangappa wrote: > Add a config option to enable schedule time slice extension. > > Signed-off-by: Prakash Sangappa > --- > include/linux/entry-common.h | 2 +- > include/linux/sched.h | 8 ++++---- > init/Kconfig | 7 +++++++ > kernel/rseq.c | 5 ++++- > kernel/sched/core.c | 12 ++++++------ > kernel/sched/debug.c | 2 +- > kernel/sched/syscalls.c | 3 ++- > 7 files changed, 25 insertions(+), 14 deletions(-) > > diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h > index d4fa952e394e..351c9dc159bc 100644 > --- a/include/linux/entry-common.h > +++ b/include/linux/entry-common.h > @@ -402,7 +402,7 @@ static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs) > CT_WARN_ON(ct_state() != CT_STATE_KERNEL); > > /* reschedule if sched delay was granted */ > - if (IS_ENABLED(CONFIG_RSEQ) && current->sched_time_delay) > + if (IS_ENABLED(CONFIG_SCHED_PREEMPT_DELAY) && current->sched_time_delay) A wrapper around this would be nice. Something like sched_delay_resched()? It can also be reused in do_sched_yield() then. Thoughts? > set_tsk_need_resched(current); > > if (IS_ENABLED(CONFIG_PROVE_LOCKING)) { [..snip..] > diff --git a/init/Kconfig b/init/Kconfig > index ce76e913aa2b..2f5f603d175a 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -1130,6 +1130,13 @@ config SCHED_MM_CID > def_bool y > depends on SMP && RSEQ > > +config SCHED_PREEMPT_DELAY > + def_bool y > + depends on SMP && RSEQ && SCHED_HRTICK and then you can avoid the ugly "!IS_ENABLED(CONFIG_SCHED_HRTICK)" checks and keep all the SCHED_PREEMPT_DELAY bits in one place without the need to put them in the "#ifdef CONFIG_SCHED_HRTICK" block. Also, are we settling for 30us delay for PREEMPT_RT too or should this also include "&& !PREEMPT_RT"? > + help > + This feature enables a thread to request extending its time slice on > + the cpu by delaying preemption. > + > config UCLAMP_TASK_GROUP > bool "Utilization clamping per group of tasks" > depends on CGROUP_SCHED -- Thanks and Regards, Prateek