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Thu, 6 Aug 2026 12:15:18 +0000 (GMT) Message-ID: <8d407e07-6c7d-49db-947f-e7ba6a30f6d6@linux.ibm.com> Date: Thu, 6 Aug 2026 17:45:17 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 0/6] sched: dynamic: Simplify PREEMPT_DYNAMIC To: Mark Rutland , linux-kernel@vger.kernel.org Cc: frederic@kernel.org, jstultz@google.com, juri.lelli@redhat.com, meted@linux.ibm.com, mingo@redhat.com, peterz@infradead.org, ruanjinjie@huawei.com, tglx@linutronix.de, vincent.guittot@linaro.org, vschneid@redhat.com References: <20260803191731.3244294-1-mark.rutland@arm.com> Content-Language: en-US From: Shrikanth Hegde In-Reply-To: <20260803191731.3244294-1-mark.rutland@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Info: AW1haW4tMjYwODA2MDA5MyBTYWx0ZWRfX0z2qki40Mz+c ANH2objTVKoiopOtxO7y1zLn6JPL1RaTe3XkLSkZ+XZecE/UHYSzCLG4his1+zNpbVPEg1U7PKM K7B5n5QjCP7MhFNJZvJeAa4m+F/x0nw= X-Authority-Analysis: v=2.4 cv=I7VVgtgg c=1 sm=1 tr=0 ts=6a747adc cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VnNF1IyMAAAA:8 a=e4rvWIFdc8uHRr-XdvkA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODA2MDA5MyBTYWx0ZWRfX15XGq7Aq6i1g ADOkayJuPG2EQ0Befvr/iguwSOpISq/NnUHX6AknQuU1TCz3u5+ulBayDh4l+rarWXJNrZJ9QJd U2ie0ho8FJq9H7CBUX2HgHn4V9P2mpuyrNnCCxpkjNavYZepL5swoJFYq0SX//bihZ2vRp9YG6/ rfl93mxJBAMf7+twP80QI7LpooF5MkJJ+hCEPHi60xq5Yd5gHf8aRs8w3lC6zrn60Bej5iu5Xhe y/vEvccl9BDhKXOvGLocd66LURooh+Bd0UXoovSxWiAEhjcHFwInE1odopR/QyxudyGDMMgjUF5 51Y0TU5/CTIDxig5EXMhwD2eCFWxTQULfgUI3BbCXXdinc+3X+5JB41R+9+jeXrwurhGMmuFgLj iJv9Vd3iKZ+UHweE7KafSYTKhzIqfU8HOizCbyqm1q8cPhTPBAvMlUljgedjqcdkXu9FEdlUEKW 0wm7fIOSy0Q+/apKeUA== X-Proofpoint-ORIG-GUID: oUuG-HgmbJ06GJ94Lr3syryou7JC5M4s X-Proofpoint-GUID: ahZbdYvf8TCPGUlpjMDgY133ugBn8lzc X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-05_06,2026-08-05_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 impostorscore=0 clxscore=1015 priorityscore=1501 suspectscore=0 malwarescore=0 adultscore=0 lowpriorityscore=0 phishscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608060093 On 8/4/26 12:47 AM, Mark Rutland wrote: > All architectures which currently suppoort PREEMPT_DYNAMIC select > ARCH_HAS_PREEMPT_LAZY. On architectures which select > ARCH_HAS_PREEMPT_LAZY, it has not been possible to select the NONE and > VOLUNTARY preemption models since v7.0 due to commit: > > 7dadeaa6e851 ("sched: Further restrict the preemption modes") > > Hence in practice PREEMPT_DYNAMIC no longer supports the NONE or > VOLUNTARY preemption models. > > This series makes the de-facto situation official by making > PREEMPT_DYNAMIC depend on ARCH_HAS_PREEMPT_LAZY, and removing redundant > code. > > Since v1, I've had to rebase atop v7.2-rc4 to avoid a conflict with > commit: > > a2c02aa0c6ca ("powerpc: Remove dead non-preemption code") > > Given this is now late in the cycle, and given the tip:sched/core branch > is based on v7.2-rc1, I suspect tip folk might not want to queue this > now. Please let me know what you'd prefer; I'm happy to rebase and > resend after v7.3-rc1. > > Since v1: > * Rebase to v7.2-rc4 > * Apply Revied-by tags. > * Fix typos in commit messages. > * Add patch to cleanup accessors (per Shrikanth's comment) > > Mark. > I have tested with and without PREEMPT_DYNAMIC for lazy/full. I haven't observed anything odd. For the series, Reviewed-by: Shrikanth Hegde Tested-by: Shrikanth Hegde > Mark Rutland (6): > sched: dynamic: Make PREEMPT_DYNAMIC depend on ARCH_HAS_PREEMPT_LAZY > sched: dynamic: Simplify {cond,might}_resched() > sched: dynamic: Simplify preempt_schedule{,_notrace}() > sched: dynamic: Simplify irqentry_exit_cond_resched() > sched: dynamic: Remove HAVE_PREEMPT_DYNAMIC_{CALL,KEY} > sched: dynamic: Simplify preempt model accessors > > arch/Kconfig | 38 ------- > arch/arm64/Kconfig | 1 - > arch/arm64/include/asm/preempt.h | 10 -- > arch/loongarch/Kconfig | 1 - > arch/powerpc/Kconfig | 1 - > arch/riscv/Kconfig | 1 - > arch/s390/Kconfig | 1 - > arch/s390/include/asm/preempt.h | 11 -- > arch/x86/Kconfig | 1 - > arch/x86/include/asm/preempt.h | 28 ----- > include/asm-generic/preempt.h | 10 -- > include/linux/irq-entry-common.h | 17 +-- > include/linux/kernel.h | 20 ---- > include/linux/preempt.h | 20 ++-- > include/linux/sched.h | 31 +----- > kernel/Kconfig.preempt | 9 +- > kernel/entry/common.c | 17 +-- > kernel/sched/core.c | 180 +------------------------------ > 18 files changed, 23 insertions(+), 374 deletions(-) >