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Thu, 24 Jul 2025 16:16:30 +0000 From: Prakash Sangappa To: linux-kernel@vger.kernel.org Cc: peterz@infradead.org, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, tglx@linutronix.de, bigeasy@linutronix.de, kprateek.nayak@amd.com, vineethr@linux.ibm.com, prakash.sangappa@oracle.com Subject: [PATCH V7 07/11] sched: Add API to indicate not to delay scheduling Date: Thu, 24 Jul 2025 16:16:21 +0000 Message-ID: <20250724161625.2360309-8-prakash.sangappa@oracle.com> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20250724161625.2360309-1-prakash.sangappa@oracle.com> References: <20250724161625.2360309-1-prakash.sangappa@oracle.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-07-24_02,2025-07-24_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 adultscore=0 bulkscore=0 suspectscore=0 mlxscore=0 phishscore=0 mlxlogscore=999 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2505160000 definitions=main-2507240123 X-Authority-Analysis: v=2.4 cv=eqbfzppX c=1 sm=1 tr=0 ts=68825c60 b=1 cx=c_pps a=zPCbziy225d3KhSqZt3L1A==:117 a=zPCbziy225d3KhSqZt3L1A==:17 a=Wb1JkmetP80A:10 a=yPCof4ZbAAAA:8 a=xGzrbLGfahxIBTsCyEoA:9 cc=ntf awl=host:12061 X-Proofpoint-GUID: _qVD9nUPXC0Uv4aUR5V7ymW9OJv8kQxb X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNzI0MDEyMyBTYWx0ZWRfX5idxh2+P0Di7 v0ungqGPyA2dkieZ7krOSAN0BH8q3BbDSHDVag0/y+0+XtmWICnnBrv60x8g+GYmxWp5R+OtHxN uDChuSzHCqDw6R6kUbDsa1SZaABMxRsxjcKLz4VCZp8kAF3IS3U+L5deO4y0lkfbqSN9Us6u7Gw s3yW6YwQOe3Z5M0hty6k3qoe0G/A8pB7fN9RWgkt1/wLTo9WFj5Cy1f1cFL3JT81Zn0vbgKczlU rb8D62aHKF2GCK1EUyoJiz3wKrr0TO4taVarmdZiDYmVvAXlFFbfy4tcmKYcFY9yLgnxzdtiGG+ 1CphUgi8IZk7HM9F9g3gVcbZAz/kRHUY7J7DwXmW9K6ZeBamoCTu9jmZgZd3VYigHGgUdCxdiyH sR48IULXEa3Gkk4OZU6bjQmY5KTOEsgeT25zF6xQkOLPRNWLRxL0k8/SNAB/5JO6yRy9KiEE X-Proofpoint-ORIG-GUID: _qVD9nUPXC0Uv4aUR5V7ymW9OJv8kQxb Content-Type: text/plain; charset="utf-8" Add an API for user threads to request scheduler to not delay scheduling it when woken up to run. This is allowed only for RT threads. Suggested-by: Thomas Gleixner Signed-off-by: Prakash Sangappa --- include/linux/sched.h | 1 + include/uapi/linux/prctl.h | 3 +++ kernel/sys.c | 18 ++++++++++++++++++ 3 files changed, 22 insertions(+) diff --git a/include/linux/sched.h b/include/linux/sched.h index 5c5868c555f0..3e8eb64658d1 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1062,6 +1062,7 @@ struct task_struct { #endif unsigned in_nf_duplicate:1; unsigned rseq_delay_resched:2; + unsigned sched_nodelay:1; #ifdef CONFIG_PREEMPT_RT struct netdev_xmit net_xmit; #endif diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h index 6f9912c65595..907300cd4469 100644 --- a/include/uapi/linux/prctl.h +++ b/include/uapi/linux/prctl.h @@ -379,4 +379,7 @@ struct prctl_mm_map { # define PR_FUTEX_HASH_GET_SLOTS 2 # define PR_FUTEX_HASH_GET_IMMUTABLE 3 =20 +/* TASK sched nodelay request */ +#define PR_SET_SCHED_NODELAY 79 +#define PR_GET_SCHED_NODELAY 80 #endif /* _LINUX_PRCTL_H */ diff --git a/kernel/sys.c b/kernel/sys.c index a088a6b1ac23..2f8b4512c6e4 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -2890,6 +2890,24 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, a= rg2, unsigned long, arg3, case PR_FUTEX_HASH: error =3D futex_hash_prctl(arg2, arg3, arg4); break; + case PR_SET_SCHED_NODELAY: + if (arg3 || arg4 || arg5) + return -EINVAL; + if (current->sched_class !=3D &rt_sched_class) + return -EINVAL; + if (arg2) + current->sched_nodelay =3D 1; + else + current->sched_nodelay =3D 0; + break; + case PR_GET_SCHED_NODELAY: + if (arg2 || arg3 || arg4 || arg5) + return -EINVAL; + if (current->sched_class !=3D &rt_sched_class) + return -EINVAL; + error =3D (current->sched_nodelay =3D=3D 1); + break; + default: trace_task_prctl_unknown(option, arg2, arg3, arg4, arg5); error =3D -EINVAL; --=20 2.43.5