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Mon, 5 Jan 2026 14:38:18 +0000 (GMT) Message-ID: <58a80940-a104-4932-a2f2-f0c6a1a205af@linux.ibm.com> Date: Mon, 5 Jan 2026 20:08:17 +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: [REGRESSION] sched/fair: Reimplement NEXT_BUDDY to align with EEVDF goals To: Ryan Roberts Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Aishwarya TCV , Dietmar Eggemann , Mel Gorman , "Peter Zijlstra (Intel)" References: <20251112122521.1331238-3-mgorman@techsingularity.net> <176339661525.498.7070393041762616565.tip-bot2@tip-bot2> <4b96909a-f1ac-49eb-b814-97b8adda6229@arm.com> <756efd17-682f-4ffc-b8d9-dbb2517bc152@arm.com> Content-Language: en-US From: Shrikanth Hegde In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=P4s3RyAu c=1 sm=1 tr=0 ts=695bccde cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=vUbySO9Y5rIA:10 a=VkNPw1HP01LnGYTKEx00:22 a=sBzgBBTEjH5M-E1ilPsA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: sqGVMvOZUY2tyGIiqXdw-gpFL2mhp01I X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTA1MDEyNSBTYWx0ZWRfXwBAG/KiRItOT X7D8q6vMFsZJadfnJ37ngt8iPAO8CwASDLYWfI/REOBggxsmjJMrhzfi/oJ7apT6TnRE+r7wswV r/HLeFqkSFL28+UPEofg4L+r0eaCeKZ4Haq1c4pl0yUG78KN8j9mPZoEV9tgJZzzz5gbkAj54O1 R+8VbDtXUvlPDz74HtLoX3SpH4NSqQxu//Nmtaanj2zBOK7hSUaontP7gOK6q/3ZRF8Z5Ij6HL4 yht9xuZ2l1AqQkgjyNkyMDylsBB4nPAzS4IuclB5Xe6LIaJDM6EZKx4qi7nns7ydtGMjH9v2ki/ 667sXKvjTYG7tAWnIhdN/TPzNTXoA6WyEc3Su/Nslwi3jgP9zM1z7sn1K6eep5jP+a1ApbGOGKW Lq3gt+ENL9+mh0uFNAdl4viK4PRETcJiEA5RSZId5/0BypWls/Ba/qKCAKXpi39P3eUsjh+lI6y FVI38n8zpTWY7DkK+gg== X-Proofpoint-GUID: sqGVMvOZUY2tyGIiqXdw-gpFL2mhp01I X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2026-01-05_01,2026-01-05_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 bulkscore=0 priorityscore=1501 clxscore=1011 suspectscore=0 phishscore=0 adultscore=0 spamscore=0 impostorscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2512120000 definitions=main-2601050125 Hi Ryan, >> node distances: >> node 0 1 >> 0: 10 20 >> 1: 20 10 >> >> Whereas I assume the Graviton3 has 64 CPUs (cores) flat in a single MC >> domain? I guess topology has influence in benchmark numbers here as well. > > I can't easily enable scheduler debugging right now (which I think is needed to > get this info directly?). But that's what I'd expect, yes. lscpu confirms there > is a single NUMA node and topology for cpu0 gives this if it helps: If you dump /proc/schedstat it should give you topology info as well. (you will need to parse it depending on which CPU you are looking this from)