From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A734ACCFA03 for ; Mon, 3 Nov 2025 08:33:38 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0FA788E0043; Mon, 3 Nov 2025 03:33:38 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0AB358E002A; Mon, 3 Nov 2025 03:33:38 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E66A88E0043; Mon, 3 Nov 2025 03:33:37 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id CF9F98E002A for ; Mon, 3 Nov 2025 03:33:37 -0500 (EST) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 84F521A0AE5 for ; Mon, 3 Nov 2025 08:33:37 +0000 (UTC) X-FDA: 84068632074.29.FD1B1CA Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by imf20.hostedemail.com (Postfix) with ESMTP id E9B981C0002 for ; Mon, 3 Nov 2025 08:33:34 +0000 (UTC) Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=ibm.com header.s=pp1 header.b=SIJzn+1B; spf=pass (imf20.hostedemail.com: domain of sshegde@linux.ibm.com designates 148.163.156.1 as permitted sender) smtp.mailfrom=sshegde@linux.ibm.com; dmarc=pass (policy=none) header.from=ibm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1762158815; a=rsa-sha256; cv=none; b=w+tqGl43/YM9N4raaaKbazWv69Yz0AzE4DbC7lk2b0Ygksmea1nu6IRJAsWylxe5oXJU+V XtvL3p8e9krwcaLBC2TeF/m20abkut7/AKBX337ABwe+B9c6wf5Q/G8SRypiv3Jy05Ifjg 4zzvPO2eQPCmz0uMXIeIwjQV/tLxNt8= ARC-Authentication-Results: i=1; imf20.hostedemail.com; dkim=pass header.d=ibm.com header.s=pp1 header.b=SIJzn+1B; spf=pass (imf20.hostedemail.com: domain of sshegde@linux.ibm.com designates 148.163.156.1 as permitted sender) smtp.mailfrom=sshegde@linux.ibm.com; dmarc=pass (policy=none) header.from=ibm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1762158815; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=6kvXegtnHGH2dvhngivPl8vSn9VVnbxianx2ml6At6Q=; b=uSyPmIjMvojmAU11Trx/EKbNBPPICxbS5P5LmWvtXSjbK4KkuMdaszjze2HVHHddKN1wZ4 XGlXn9a3ACNyy7bL83YhBFwivg000rMEW0NOsf36p38cVVjTyWnlcjdpDq/2AP2uLSV5as yJwYErvVX8fLGBWFD80e/FyUZRCWOic= Received: from pps.filterd (m0356517.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 5A2KFI8K004420; Mon, 3 Nov 2025 08:32:28 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=6kvXeg tnHGH2dvhngivPl8vSn9VVnbxianx2ml6At6Q=; b=SIJzn+1B6W9oM2eaoy/YHg eBBigTFYyvOI9FqFVbAxNQBJk7OsJkIcL71Bfna6VZUkqh40c7GapUFYZ5iF8sRv Gr8dTXMymRtZJ8s++yexWv1ij7wo6VYhShrZhVDq41yj75ph0JeGVCKADK/YHtTq GX3MIMDZ/N5qqAEIbGF00Q5htF6MOC+XL4hF518BX18l+iJjxcQbmu4bDG1zmjC4 JaRrWPwAdwUgpIOYFdxBzdZMRCWUzsW/HgM451x3+JWx1KfcwQmlDNOkYt4NhTIW gRD9YIaV0/uJm8zB4i1DBFMoHs18pKBmB/HXGu5E8lZ+lxXr3R2rXIwqr6iKj5Pg == Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4a59xbnkvs-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 03 Nov 2025 08:32:27 +0000 (GMT) Received: from m0356517.ppops.net (m0356517.ppops.net [127.0.0.1]) by pps.reinject (8.18.1.12/8.18.0.8) with ESMTP id 5A38WQmQ029518; Mon, 3 Nov 2025 08:32:27 GMT Received: from ppma11.dal12v.mail.ibm.com (db.9e.1632.ip4.static.sl-reverse.com [50.22.158.219]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4a59xbnkvq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 03 Nov 2025 08:32:26 +0000 (GMT) Received: from pps.filterd (ppma11.dal12v.mail.ibm.com [127.0.0.1]) by ppma11.dal12v.mail.ibm.com (8.18.1.2/8.18.1.2) with ESMTP id 5A34SfIE012891; Mon, 3 Nov 2025 08:32:25 GMT Received: from smtprelay07.fra02v.mail.ibm.com ([9.218.2.229]) by ppma11.dal12v.mail.ibm.com (PPS) with ESMTPS id 4a5y81mbvw-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 03 Nov 2025 08:32:25 +0000 Received: from smtpav02.fra02v.mail.ibm.com (smtpav02.fra02v.mail.ibm.com [10.20.54.101]) by smtprelay07.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 5A38WNYw44106174 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 3 Nov 2025 08:32:23 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C27F220040; Mon, 3 Nov 2025 08:32:23 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 16F2220043; Mon, 3 Nov 2025 08:32:13 +0000 (GMT) Received: from [9.109.215.252] (unknown [9.109.215.252]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 3 Nov 2025 08:32:12 +0000 (GMT) Message-ID: Date: Mon, 3 Nov 2025 14:02:11 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 23/29] context-tracking: Introduce work deferral infrastructure To: Valentin Schneider Cc: Nicolas Saenz Julienne , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Arnaldo Carvalho de Melo , Josh Poimboeuf , Paolo Bonzini , Arnd Bergmann , Frederic Weisbecker , "Paul E. McKenney" , Jason Baron , Steven Rostedt , Ard Biesheuvel , Sami Tolvanen , "David S. Miller" , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Uladzislau Rezki , Mathieu Desnoyers , Mel Gorman , Andrew Morton , Masahiro Yamada , Han Shen , Rik van Riel , Jann Horn , Dan Carpenter , Oleg Nesterov , Juri Lelli , Clark Williams , Yair Podemsky , Marcelo Tosatti , Daniel Wagner , Petr Tesarik , linux-kernel@vger.kernel.org, linux-mm@kvack.org, rcu@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linux-riscv@lists.infradead.org, linux-arch@vger.kernel.org, linux-trace-kernel@vger.kernel.org References: <20251010153839.151763-1-vschneid@redhat.com> <20251010153839.151763-24-vschneid@redhat.com> Content-Language: en-US From: Shrikanth Hegde In-Reply-To: <20251010153839.151763-24-vschneid@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMTAxMDAyMSBTYWx0ZWRfXyZF7uxWMbR9h eLK/nkDGQm3o/vMS6b4dMArF21TNJ6CaqoI+fi7VPIcu7OWjh13TfAaGOyTxh1gnwQIWiBKHjJa 4uMwIrzLslo+qUygbHd9488ZCjL6vK5iXuiWUNX6ThTOzJBP1PKCUz5zZmvloNgyToR45jE2irN a4EYP7E5d99vyLe0EnPUaY+AWXCKsxBO2ENMsQJ0K7+9kC0+hwsMybY4fCkeMcwmUxF0SvKxntf G1Y18toiIF/maL5RFi7povbdJ4FJNPvHT8auC2LdGyFW5VpJAL0soYtskChjteGM2wfpc+kcC7y KDSiIb0W+R7wCTgyXcXkjXUndM3ScPyUHlasPD5janXDgGwLZxidSrdWYD0Sch6Yd3oNTOJv1+T flE5Wy2KQc8LqVOKJgn3Dc1iG4Hf4Q== X-Proofpoint-GUID: U84lOeDC5Q0AhrPIqcAHknHeCkhsE8rA X-Authority-Analysis: v=2.4 cv=OdCVzxTY c=1 sm=1 tr=0 ts=6908689b cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=IkcTkHD0fZMA:10 a=6UeiqGixMTsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VwQbUJbxAAAA:8 a=JfrnYn6hAAAA:8 a=20KFwNOVAAAA:8 a=e3ynTO8eh5RAdg4_BR0A:9 a=QEXdDO2ut3YA:10 a=1CNFftbPRP8L7MoqJWF3:22 a=UhEZJTgQB8St2RibIkdl:22 a=Z5ABNNGmrOfJ6cZ5bIyy:22 a=QOGEsqRv6VhmHaoFNykA:22 X-Proofpoint-ORIG-GUID: Yw4-ly9gm_lGmLrDsIj0uqTuFktFQQKI 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=2025-11-02_02,2025-10-29_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 adultscore=0 spamscore=0 suspectscore=0 impostorscore=0 lowpriorityscore=0 priorityscore=1501 clxscore=1011 phishscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510240000 definitions=main-2511010021 X-Rspam-User: X-Stat-Signature: duyh5389x68aj3w7aiyyywmeup5tbbef X-Rspamd-Queue-Id: E9B981C0002 X-Rspamd-Server: rspam09 X-HE-Tag: 1762158814-214985 X-HE-Meta: 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 Kn9l8vzf 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Valentin. On 10/10/25 9:08 PM, Valentin Schneider wrote: > smp_call_function() & friends have the unfortunate habit of sending IPIs to > isolated, NOHZ_FULL, in-userspace CPUs, as they blindly target all online > CPUs. > > Some callsites can be bent into doing the right, such as done by commit: > > cc9e303c91f5 ("x86/cpu: Disable frequency requests via aperfmperf IPI for nohz_full CPUs") > > Unfortunately, not all SMP callbacks can be omitted in this > fashion. However, some of them only affect execution in kernelspace, which > means they don't have to be executed *immediately* if the target CPU is in > userspace: stashing the callback and executing it upon the next kernel entry > would suffice. x86 kernel instruction patching or kernel TLB invalidation > are prime examples of it. > > Reduce the RCU dynticks counter width to free up some bits to be used as a > deferred callback bitmask. Add some build-time checks to validate that > setup. > > Presence of CT_RCU_WATCHING in the ct_state prevents queuing deferred work. > > Later commits introduce the bit:callback mappings. > > Link: https://lore.kernel.org/all/20210929151723.162004989@infradead.org/ > Signed-off-by: Nicolas Saenz Julienne > Signed-off-by: Valentin Schneider > --- > arch/Kconfig | 9 +++ > arch/x86/Kconfig | 1 + > arch/x86/include/asm/context_tracking_work.h | 16 +++++ > include/linux/context_tracking.h | 21 ++++++ > include/linux/context_tracking_state.h | 30 ++++++--- > include/linux/context_tracking_work.h | 26 ++++++++ > kernel/context_tracking.c | 69 +++++++++++++++++++- > kernel/time/Kconfig | 5 ++ > 8 files changed, 165 insertions(+), 12 deletions(-) > create mode 100644 arch/x86/include/asm/context_tracking_work.h > create mode 100644 include/linux/context_tracking_work.h > > diff --git a/include/linux/context_tracking_work.h b/include/linux/context_tracking_work.h > new file mode 100644 > index 0000000000000..c68245f8d77c5 > --- /dev/null > +++ b/include/linux/context_tracking_work.h > @@ -0,0 +1,26 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +#ifndef _LINUX_CONTEXT_TRACKING_WORK_H > +#define _LINUX_CONTEXT_TRACKING_WORK_H > + > +#include > + > +enum { > + CT_WORK_n_OFFSET, > + CT_WORK_MAX_OFFSET > +}; > + > +enum ct_work { > + CT_WORK_n = BIT(CT_WORK_n_OFFSET), > + CT_WORK_MAX = BIT(CT_WORK_MAX_OFFSET) > +}; > + > +#include > + It fails to compile on powerpc (likey any arch other than x86) In file included from ./include/linux/context_tracking_state.h:8, from ./include/linux/hardirq.h:5, from ./include/linux/interrupt.h:11, from ./include/linux/kernel_stat.h:8, from ./include/linux/cgroup.h:27, from ./include/linux/memcontrol.h:13, from ./include/linux/swap.h:9, from ./include/linux/suspend.h:5, from arch/powerpc/kernel/asm-offsets.c:21: ./include/linux/context_tracking_work.h:17:10: fatal error: asm/context_tracking_work.h: No such file or directory 17 | #include | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Gating works for compile, but no benefit of the series. +#ifdef HAVE_CONTEXT_TRACKING_WORK #include +#endif I have been trying to debug/understand the issue seen with isolcpus= and nohz_full=. system is idle, even then it occasionally woken up to do some work. So I was interesting if this series can help.