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Sat, 23 May 2026 17:40:41 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (smtpav04.fra02v.mail.ibm.com [10.20.54.103]) by smtprelay07.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 64NHebBS43843872 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 23 May 2026 17:40:37 GMT Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 46C7920043; Sat, 23 May 2026 17:40:37 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8882C20040; Sat, 23 May 2026 17:40:35 +0000 (GMT) Received: from li-7bb28a4c-2dab-11b2-a85c-887b5c60d769.ibm.com.com (unknown [9.39.18.40]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Sat, 23 May 2026 17:40:35 +0000 (GMT) From: Shrikanth Hegde To: maddy@linux.ibm.com, linuxppc-dev@lists.ozlabs.org, tglx@kernel.org Cc: sshegde@linux.ibm.com, christophe.leroy@csgroup.eu, linux-kernel@vger.kernel.org Subject: [PATCH 0/3] powerpc/irq: Use optimizations for /proc/interrupts Date: Sat, 23 May 2026 23:10:13 +0530 Message-ID: <20260523174016.999456-1-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.51.0 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: sOCiUXPmCzneE4ju14DS_UnoRXVZesfL X-Authority-Analysis: v=2.4 cv=Sq2gLvO0 c=1 sm=1 tr=0 ts=6a11e69a cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VwQbUJbxAAAA:8 a=ZHew1V-Ef7zmNSL-XegA:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIzMDE4MCBTYWx0ZWRfX/tKj4mYNrfx+ usC4IIBoLvRf4fpFn1mjxytOpY7be5zr8kUcVkYRmKCOtuEZX6ANB1HtfvMVR7cTcSGFsOTS9rf 9GmqEpR0arcXot/6vv5GEAZWHqxjgMqUHoksMw8YEaNdtUilCfnoRp2KItX4nnTPOZgP1BrhjTm eMyiJ3biks5ayO/Qjf4OabvU1dLDSqF0X8Krea7jHYfuYsyh7piwI4wwOaDeywa6n6ZOUj8MItj ghzwd0SOpLbAnE2IMLcj3REGQ7dt9V6m0tV6I2wNjD3M21t389ey8es6CSHVk4qQH+Ova97dPvr OWZ+Dy5cfKXJ5q2xs77CUzg5pCwQqBLpsjWDkqJFyLFKUtomhTROslwMfb5F29Cge9dJ1N6BsGM Yg/+dml9gaV/JV1FjpHdE+an8lk1u+GQFfrr/znI9+1YDynxRupGkQWYCu0N0kCEPBdexr0k9SG qsCaILVwJGEPdKGIq5Q== X-Proofpoint-ORIG-GUID: sOCiUXPmCzneE4ju14DS_UnoRXVZesfL X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-23_05,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 priorityscore=1501 phishscore=0 impostorscore=0 malwarescore=0 lowpriorityscore=0 adultscore=0 clxscore=1015 suspectscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605230180 This series is based on work by Thomas Gleixner[1]. There are several optimization which helps to bring the time taken to read /proc/interrupts. Though it is not in fastpaths, still many tools read it often and this reduction in time will save meaningful amount of cycle over the long duration. [1]: https://lore.kernel.org/all/20260517194421.705253664@kernel.org/ Bulk of the design/code is copied from Thomas's work on x86. powerpc had exact pattern which made it quite easy to port. Using micro-loops[2] of reading /proc/interrupts shows real benefit of the series. Bulk of the gain is already achieved using Thomas's series[1]. This series on top provide some more benefits. As the system size goes up, benefits could be more. [2]: https://lore.kernel.org/all/87jysxw65f.ffs@tglx/ ======== Performance Data ================== Time taken to read /proc/interrupts 1000 times[2] Base : 103us v6 : 63us v6+patch 1+2 : 57us v6+patch 1+2+3 : 54us Base: tip/master at c991e3897ead ("Merge branch into tip/master: 'x86/tdx'") Depends on v6[1] to be applied first. Shrikanth Hegde (3): powerpc/irq: Move __softirq_pending out of irq_stat powerpc/irq: Make irqstats array based powerpc/irq: Suppress unlikely interrupt stats by default arch/powerpc/include/asm/hardirq.h | 31 ++++--- arch/powerpc/kernel/dbell.c | 2 +- arch/powerpc/kernel/irq.c | 131 +++++++++++++++-------------- arch/powerpc/kernel/time.c | 6 +- arch/powerpc/kernel/traps.c | 11 +-- arch/powerpc/kernel/watchdog.c | 2 +- 6 files changed, 95 insertions(+), 88 deletions(-) -- 2.47.3