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Shenoy" , Vincent Guittot , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Hillf Danton , Shrikanth Hegde , Jianyong Wu , Yangyu Chen , Tingyin Duan , Vern Hao , Len Brown , Aubrey Li , Zhao Liu , Chen Yu , Chen Yu , Libo Chen , Adam Li , Tim Chen , linux-kernel@vger.kernel.org, Madadi Vineeth Reddy References: <20251015122125.GU3289052@noisy.programming.kicks-ass.net> <782009c48dbde2cb2912f4d5dc573ecfbd2c1087.camel@linux.intel.com> Content-Language: en-US From: Madadi Vineeth Reddy In-Reply-To: <782009c48dbde2cb2912f4d5dc573ecfbd2c1087.camel@linux.intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: zeoFzgJS2yYASJfBOUisTtk_aYIUas0v X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMDE4MDAyMiBTYWx0ZWRfX1S3h0DT3tQCw YM6EYEd1EkxQKS1/kVYLAUcx/1OnFJajioWtsr07Ij+MrX8g5CNRFizTV+Y2+EO0BtbN8fxwR8o dR6y/RbDSCMYozpxb7++g9wSG63O5cDck+hpuQbyOPo4wVxc/p50PcBjH1TZcwqzJvhdhEB8/T3 cb/ePN+zcFR1ZaxgNgEz73E+6S32e1MMcWcznFsQdg5tM7nZJbh9FotiTjbjyBpHSmU+lZaZ1+4 XoWwlqnvlHiyoC33Gp9tLhY7Kw+OCvnCPB8WVQcuzM8Sx4G/ElEncg9O3nxsHY1HV2BlxR4OzR0 aKsXIfNvJJTHm7fJmkXVh6KBad3jIPRhelhWZAhvcT0Uw5H8yG/i7N+PErf1dHy31oVvL3DLjaL ovu8UEHOZ/JgedF10E79JujarN3rkA== X-Authority-Analysis: v=2.4 cv=MIJtWcZl c=1 sm=1 tr=0 ts=68f74445 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=x6icFKpwvdMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=Ypq1MTz9OACtASZl0d4A:9 a=QEXdDO2ut3YA:10 a=nl4s5V0KI7Kw-pW0DWrs:22 a=pHzHmUro8NiASowvMSCR:22 a=xoEH_sTeL_Rfw54TyV31:22 X-Proofpoint-ORIG-GUID: 27cN7s8cZLE7jZxX0WeO7pNS413GISEC X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-10-20_07,2025-10-13_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 spamscore=0 phishscore=0 lowpriorityscore=0 adultscore=0 clxscore=1015 impostorscore=0 bulkscore=0 priorityscore=1501 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510020000 definitions=main-2510180022 On 16/10/25 02:11, Tim Chen wrote: > On Wed, 2025-10-15 at 14:21 +0200, Peter Zijlstra wrote: >> On Sat, Oct 11, 2025 at 11:24:45AM -0700, Tim Chen wrote: >>> Each runqueue is assigned a static array where each element tracks >>> the number of tasks preferring a given LLC, indexed from 0 to >>> NR_LLCS. >>> [snip] >> >>> >>> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h >>> index 3ab64067acc6..b801d32d5fba 100644 >>> --- a/kernel/sched/sched.h >>> +++ b/kernel/sched/sched.h >>> @@ -1101,6 +1101,7 @@ struct rq { >>> #ifdef CONFIG_SCHED_CACHE >>> unsigned int nr_pref_llc_running; >>> unsigned int nr_llc_running; >>> + unsigned int nr_pref_llc[NR_LLCS]; >> >> Gah, yeah, lets not do this. Just (re)alloc the thing on topology >> changes or something. > > Will have to think about how to keep the tasks' preference > consistent with nr_pref_llc with the new array. Perhaps > make it size of NR_CPUS so we will allocate > once and don't have to resize and reallocate it, and > fill it back up with the right data. > > Tim IIUC, what Peter meant is to dynamically allocate the array size based on the actual number of LLCs computed in build_sched_domains() or somesuch rather than statically allocating NR_LLCS which is 64 by default. Making it NR_CPUS would be even larger and waste more memory on systems with few LLCs. Thanks, Madadi Vineeth Reddy