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Tue, 4 Aug 2026 20:27:05 +0000 (GMT) Message-ID: <367a9709-eb79-4579-9405-fb8d89576413@linux.ibm.com> Date: Wed, 5 Aug 2026 01:57:04 +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 v4 12/17] s390/preempt: Enable HAS_SEPARATE_PREEMPT_RESCHED_BITS To: Boqun Feng , Madhavan Srinivasan , "Christophe Leroy (CS GROUP)" Cc: Ingo Molnar , Will Deacon , Waiman Long , Gary Guo , Alice Ryhl , Lyude Paul , Daniel Almeida , =?UTF-8?Q?Onur_=C3=96zkan?= , Miguel Ojeda , Danilo Krummrich , linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, Heiko Carstens , Peter Zijlstra References: <20260804161447.84806-1-boqun@kernel.org> <20260804161447.84806-13-boqun@kernel.org> Content-Language: en-US From: Shrikanth Hegde In-Reply-To: <20260804161447.84806-13-boqun@kernel.org> 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-ORIG-GUID: vMTnO9MQG_j-rTycTnHNHHVynBYTI3XE X-Proofpoint-Spam-Info: AW1haW4tMjYwODA0MDE2NCBTYWx0ZWRfX5V/F3FLCCnCq RTtCtYc/r21BcZEHNkDM0fU2bzdHeeil1kqGAbb/D1+dAna99i5scr+kbcoD0KU+wPoq3/HwuzV 6O//xjdEoPaP6NGeOyg5liRDuGFfvuI= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODA0MDE2NCBTYWx0ZWRfXzk/gl3B0l0c5 4WxCl5BxsWbZlIiZrRs67fbPfbdvkySNDgVo4Ahpb7RF2rZbfstMLCT92kWw1CiETWkdtkzyunF Wv/CQRbyc+ISx9eZb7Mr0MGSOiexTFuDfhVYKXAk5G4DujZLXR3LPsn9zEW4IMO/8P5eDZ1kjW1 dKq/GsnbdNjeg/uXvkCpdLhhqytD0i3H6aaqH/orX2tQzqxTbvaitfNphOEqOmtCi+9sg9eVJvA nOBLd0jO+0HVobJAIum4cIfZ80bFNuYOs2Sb0Xc5rr2PGxv858or8XAr7R9nV4yN6H67noKJ6Ep bhm8bO70DEkT5+PxddRe62eDok8TG9ZOQJRMiGXKgqUtY25+UteU36xucETWp47mTM9wQtc0jxx SgSAQsTk4/JKsboX/dL08zh/8oJK1qgrlyvmyxRYjPcOiqbB0ZeeXRi8azNk7YMtPL1B0Ev5asG tNA10oK4CfkdyKVveew== X-Proofpoint-GUID: Lh6Zdyja0HSkCyWPHm8Oy2wpVokalkbN X-Authority-Analysis: v=2.4 cv=KfzidwYD c=1 sm=1 tr=0 ts=6a724b23 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=GjiJ6sYaQ7aKqrb2YAAA:9 a=QEXdDO2ut3YA:10 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=2026-08-04_05,2026-08-04_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 bulkscore=0 impostorscore=0 suspectscore=0 malwarescore=0 adultscore=0 clxscore=1015 priorityscore=1501 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-2608040164 +maddy, christophe, On 8/4/26 9:44 PM, Boqun Feng wrote: > From: Heiko Carstens > > Convert s390's preempt_count to 64 bit, and change the preempt > primitives accordingly. > > + union { > + struct { > + __u32 need_resched; /* 0x03a8 */ > + __u32 count; /* 0x03ac */ > + } preempt; > + __u64 preempt_count; /* 0x03a8 */ > + }; This is interesting. So arm64, s390 will have similar implementation w.r.t to preempt_count. I guess PoC that i was trying for ppc64 is worth pursuing even more, since ppc64 is one missing major arch which still uses old method of querying tif_need_resched. With similar change ppc64 can set HAS_SEPARATE_PREEMPT_RESCHED_BITS too.