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Thu, 13 Aug 2026 06:50:44 +0000 (GMT) Received: from [9.224.76.67] (unknown [9.224.76.67]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 13 Aug 2026 06:50:44 +0000 (GMT) Message-ID: Date: Thu, 13 Aug 2026 08:50:43 +0200 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] Re: [PATCH v10 00/12] sched, steal_governor: Introduce preferred CPUs and steal-driven vCPU backoff To: Yury Norov , "Ionut Nechita (Sunlight Linux)" Cc: Shrikanth Hegde , arighi@nvidia.com, chleroy@kernel.org, christian.loehle@arm.com, corbet@lwn.net, dietmar.eggemann@arm.com, frederic@kernel.org, gregkh@linuxfoundation.org, hdanton@sina.com, huschle@linux.ibm.com, iii@linux.ibm.com, jgross@suse.com, juri.lelli@redhat.com, kernellwp@gmail.com, kprateek.nayak@amd.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, maddy@linux.ibm.com, maz@kernel.org, mingo@kernel.org, pauld@redhat.com, pbonzini@redhat.com, peterz@infradead.org, rafael@kernel.org, rdunlap@infradead.org, rostedt@goodmis.org, seanjc@google.com, tglx@kernel.org, tj@kernel.org, tommaso.cucinotta@gmail.com, vincent.guittot@linaro.org, vineeth@bitbyteword.org, virtualization@lists.linux.dev, vschneid@redhat.com, yury.norov@gmail.com References: <20260812054033.95658-1-sshegde@linux.ibm.com> <20260812194600.52516-1-sunlightlinux@gmail.com> Content-Language: en-US From: Mete Durlu In-Reply-To: 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-Authority-Analysis: v=2.4 cv=AMtp2X5w c=1 sm=1 tr=0 ts=6a7d694a cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=ytvUXjNDRGHaUZttXtEA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: no_RzowkTuFFWN43HBrYVKw0wweS2OeI X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODEzMDA0NCBTYWx0ZWRfX7kmkn7sBut12 mAYZIy4OUVv6XC2KDQIUVliN9/u5sGqSPE/wckOsHUCCzK6arq914B+LkJh0ls8w0Kz+AJbnzgb DVxS0tyMSeEij++a1oKCrddG16kgEzAMgvTpIKruJ5/hqH1WrUadjDQ/GeO2t1SxhdRqkENXgj0 1NsFNTxzU783vqz5yxa+zJsiIYq7KtE374n1fHejPzc6FVcRMf055tRHz0mD6xyXNnx3PsMwsNt WCvql6rOcCuzE6EE/101zbweMmb2OUm6FiBM01vg69USxcJ1GYX/eUqNXC2qEROm7srk95N1vFl 4afGXdrj4zSASG6MAmgKBhgcoGhqXGXFaZFScRmjfNLUBqQu1/CLgd3V8vliRofb2LI2W1dFjyZ h7oAwmu+KmXuUWaJSdlqvRqLr2fOmHPFZ2Okh7F8+ibWmdSyCTCYcL8//TObJeWSLaFCL6F/tYK HWI+evlQngFKactSBWg== X-Proofpoint-ORIG-GUID: 2fE5d4xrKH3ReufcYIxjdH0yP9eBmjIU X-Proofpoint-Spam-Info: AW1haW4tMjYwODEzMDA0NCBTYWx0ZWRfX8x7U8lZAJsRm nyQMikEHXeCeYnbrHa1q5+ow0mF0kVw30XJ6nHIE6wF197WqqWaPqpgk2+NOarkiT7Ca0+/OknA SZkI8WPGHVZDcP8MJd5w4pdq3FvlQq0= 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=2026-08-13_02,2026-08-12_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 adultscore=0 lowpriorityscore=0 clxscore=1015 priorityscore=1501 impostorscore=0 phishscore=0 spamscore=0 bulkscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608130044 Hi all, All of the points raised by Ionut are about governor lacking certain logic for a specific arch. Considering what Shrikanth mentions under "Future Work"; """ Known Limitations & Future Work =============================== ... - Arch specific hints and framework for it as been deferred to the future. ... """ I think all of these points can be addressed better if Xen used said framework and implemented their own governor module. That way we wouldn't see an overinflated single steal_governor but instead nicely separated arch/platform specific ones, that are tailored best for their needs. The current implementation could be the fallback option if platform does not implement their own and would also serve as an example. I really think we should follow the example of cpuidle drivers and how their framework brings together so many platforms under a single roof. Thanks! -Mete