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Fri, 26 Jun 2026 13:27:48 +0000 (GMT) Received: from [9.39.23.71] (unknown [9.39.23.71]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 26 Jun 2026 13:27:47 +0000 (GMT) Message-ID: <19527132-eefd-42b2-8dbc-258d6c598a34@linux.ibm.com> Date: Fri, 26 Jun 2026 18:57:47 +0530 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 04/24] cpumask: Introduce cpu_preferred_mask To: Yury Norov Cc: Peter Zijlstra , linux-kernel@vger.kernel.org, mingo@kernel.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, kprateek.nayak@amd.com, iii@linux.ibm.com, corbet@lwn.net, tglx@kernel.org, gregkh@linuxfoundation.org, pbonzini@redhat.com, seanjc@google.com, vschneid@redhat.com, huschle@linux.ibm.com, rostedt@goodmis.org, dietmar.eggemann@arm.com, maddy@linux.ibm.com, srikar@linux.ibm.com, hdanton@sina.com, chleroy@kernel.org, vineeth@bitbyteword.org, frederic@kernel.org, arighi@nvidia.com, pauld@redhat.com, christian.loehle@arm.com, tj@kernel.org, tommaso.cucinotta@gmail.com, maz@kernel.org, rafael@kernel.org, rdunlap@infradead.org, kernellwp@gmail.com, linux-doc@vger.kernel.org References: <20260625124648.802832-1-sshegde@linux.ibm.com> <20260625124648.802832-5-sshegde@linux.ibm.com> <20260626093901.GN1181229@noisy.programming.kicks-ass.net> <20260626094153.GD2568396@noisy.programming.kicks-ass.net> <79e85557-719c-4fc8-98ad-7bdcc6add753@linux.ibm.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-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: m3HXjw3sKUFQ52aaTskLpymDsGp-hCBj X-Proofpoint-Spam-Info: AW1haW4tMjYwNjI2MDEwOSBTYWx0ZWRfX3rVOGr/UlSH4 c+XFbiLV5B971kuJEOAF0CbLnHd0gUE8lLtlf46wDOpjnUlHfR/b51dqpp5ufSmAvbERe6BtnD5 94BMOTYqiP0nzaQAmooeHx0sbcBtuXo= X-Authority-Analysis: v=2.4 cv=c62bhx9l c=1 sm=1 tr=0 ts=6a3e7e61 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=FelO9ux0wxsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=OpyquhL-vbyOqvzoqVEA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjI2MDEwOSBTYWx0ZWRfX6+xWCgvUn7mZ Mg271/iUHeKnDMANts4GCiSp26HwUHo9/Vse/lLB1qy3ARBkTdO1OlNBrHkTkX8sCVZv/GZFvXd 0RobyLcxlN68xfO+PJWxxt2kzHyEWch1qgRL0MqzT2Tj+cav5WhDVIAFGu+cICYIGqX9FN9u9y5 qb8ugmUInKTmx+QS5xe1oegFJI8RTYgQ6LAvGVCw6FRdZK1Z+IhQJFV9LlY66XTj5BR26T/oUUo 5h/yq7+aXEzzUKsRlK/MNt5P0oAZfU0nCJE61ItFXIXU2q9vCwkd+Hyfb8V5q1RUlxPrd1zzB9S WXZsZLcvtZMqCpFcxufJJsV0fgyiJmkcKaLc+UYBetlr9rA+XHlIatO9i0AXHGqFuUdITHGqm51 g0NAL87vLzwS5gyv+0MogtKt4on9A3aLlX1QIxnXAKok1gpIKEWORrjA0YlBECEIQxAercQYr8Y 4M2wLl2jyyTF3SRB23w== X-Proofpoint-ORIG-GUID: dK-1zJqJDAbgy45Md4fMiyxbGB87vV25 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-26_03,2026-06-24_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 impostorscore=0 adultscore=0 clxscore=1015 suspectscore=0 priorityscore=1501 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-2606260109 On 6/26/26 6:48 PM, Yury Norov wrote: > On Fri, Jun 26, 2026 at 06:39:48PM +0530, Shrikanth Hegde wrote: >> Hi Peter, Yury. >> >> On 6/26/26 3:11 PM, Peter Zijlstra wrote: >>> On Fri, Jun 26, 2026 at 11:39:01AM +0200, Peter Zijlstra wrote: >>>> On Thu, Jun 25, 2026 at 06:16:28PM +0530, Shrikanth Hegde wrote: >>>> >>>>> diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h >>>>> index 80211900f373..5a643d608ea6 100644 >>>>> --- a/include/linux/cpumask.h >>>>> +++ b/include/linux/cpumask.h >>>>> @@ -120,12 +120,20 @@ extern struct cpumask __cpu_enabled_mask; >>>>> extern struct cpumask __cpu_present_mask; >>>>> extern struct cpumask __cpu_active_mask; >>>>> extern struct cpumask __cpu_dying_mask; >>>>> + >>>>> +#ifdef CONFIG_PREFERRED_CPU >>>>> +extern struct cpumask __cpu_preferred_mask; >>>>> +#else >>>>> +#define __cpu_preferred_mask __cpu_active_mask >>>>> +#endif >>>> >>>> This is cure, but does it not result in set_cpu_preferred() changing >>> s/cure/cute/ >>>> active mask, and it that not somewhat unexpected behaviour? >>> s/it/is/ >>> >> >> Yes. I thought about this, but i didn't see anything bad happening apart from >> setting it twice. But I do agree, it is an eyesore when CONFIG_PREFERRED_CPU=n. >> >>> Typing hard, clearly. Also hitting 30C before noon :-( >>> >> >> Take care. Even we should have had monsoon by now. >> But its bright sunshine :( >> >>> >> >> For this reason, i had it as a function instead of macro in v4. >> Do you think we can still fallback to it? >> >> only caveat is it won't be a macro. But since it is still compile >> time optimized due to IS_ENABLED, it should be relatively ok right? >> >> +void set_cpu_preferred(unsigned int cpu, bool preferred) >> +{ >> + if (!IS_ENABLED(CONFIG_PREFERRED_CPU)) >> + return; >> + >> + assign_cpu((cpu), &__cpu_preferred_mask, (preferred)); >> +} > > #ifdef CONFIG_PREFERRED_CPU > #define set_cpu_preferred(cpu, preferred) assign_cpu((cpu), &__cpu_preferred_mask, (preferred)) > #else > #define set_cpu_preferred(cpu, preferred) {} > #endif > Ah! thanks.