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Thu, 11 Sep 2025 07:20:04 GMT Received: from smtpav02.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id F149758D79; Thu, 11 Sep 2025 06:45:27 +0000 (GMT) Received: from smtpav02.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4EAB458D50; Thu, 11 Sep 2025 06:45:18 +0000 (GMT) Received: from [9.98.110.226] (unknown [9.98.110.226]) by smtpav02.wdc07v.mail.ibm.com (Postfix) with ESMTP; Thu, 11 Sep 2025 06:45:11 +0000 (GMT) Message-ID: <8f0c39e3-af68-4f01-94e5-e63ee52864df@linux.ibm.com> Date: Thu, 11 Sep 2025 12:15:09 +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] sched: fair: drop useless cpumask_empty() in find_energy_efficient_cpu() To: Yury Norov References: <20250911023426.457745-1-yury.norov@gmail.com> Content-Language: en-US Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , linux-kernel@vger.kernel.org, Madadi Vineeth Reddy From: Madadi Vineeth Reddy In-Reply-To: <20250911023426.457745-1-yury.norov@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwOTA2MDAxMCBTYWx0ZWRfX5zPFdRRsVaJo Po7ABAhWLwofQwiJWZKqpKLYdTyZepwDaE/HD+lf19yUGP9lOTGUBx0hOc79jCqBM/BC5SDpLdY CFzPuqtDjlhWfh/U9sRhoKkOKmicVoDd0w6JJIrNr8y2Ihgovh0AfshDs2kWEq5piVgfFXkChJs 5p0iymy2Oc49nhzbLGV2DHlfdHvkc5R4bvj3AcPx5a/VkTIB1of8fqG9sMnYOzW6kDIiFUyMKq+ 95p26eWRcGLdhg0JOUNnxCZcIdc7BpT1iZ6tTTTqIhSg33bQI7yFC8H63K21NSsax3vuRkfwsGO RQEbxMrAgH2q+51dfV2U4mgXV2DBUB914hNONxTb/RyOVd3/+80TKXHqPjlKPDHb+uaLECnHOoa K0pDaduD X-Authority-Analysis: v=2.4 cv=SKNCVPvH c=1 sm=1 tr=0 ts=68c27826 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=IkcTkHD0fZMA:10 a=yJojWOMRYYMA:10 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=6Bb8fD9tztjf4PytmToA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: 3F6g7Uqw7JqiW9Dq09P6Liu43JzwoHXG X-Proofpoint-ORIG-GUID: GtCv1V-k3dSnSIgAtiOdzGH-UJb2c802 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1117,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-09-10_04,2025-09-10_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 spamscore=0 priorityscore=1501 bulkscore=0 malwarescore=0 adultscore=0 suspectscore=0 impostorscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2507300000 definitions=main-2509060010 On 11/09/25 08:04, Yury Norov wrote: > From: Yury Norov (NVIDIA) > > cpumask_empty() call is O(N) and useless, because the previous > cpumask_and() returns false for empty 'cpus'. > LGTM Reviewed-by: Madadi Vineeth Reddy Thanks, Madadi Vineeth Reddy > Signed-off-by: Yury Norov (NVIDIA) > --- > kernel/sched/fair.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index b173a059315c..7229339cbb1b 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -8320,9 +8320,7 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) > int max_spare_cap_cpu = -1; > int fits, max_fits = -1; > > - cpumask_and(cpus, perf_domain_span(pd), cpu_online_mask); > - > - if (cpumask_empty(cpus)) > + if (!cpumask_and(cpus, perf_domain_span(pd), cpu_online_mask)) > continue; > > /* Account external pressure for the energy estimation */