From nobody Mon Sep 15 13:07:11 2025 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8261AC54EBC for ; Thu, 12 Jan 2023 03:40:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236045AbjALDkw (ORCPT ); Wed, 11 Jan 2023 22:40:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39144 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235045AbjALDkq (ORCPT ); Wed, 11 Jan 2023 22:40:46 -0500 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B54F544352; Wed, 11 Jan 2023 19:40:45 -0800 (PST) Received: from kwepemm600003.china.huawei.com (unknown [172.30.72.56]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4NsqzH3cVnz16Mfg; Thu, 12 Jan 2023 11:39:07 +0800 (CST) Received: from ubuntu1804.huawei.com (10.67.174.61) by kwepemm600003.china.huawei.com (7.193.23.202) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.34; Thu, 12 Jan 2023 11:40:42 +0800 From: Yang Jihong To: , , , , , , , , CC: Subject: [PATCH] perf/core: Fix account interrupt throttle Date: Thu, 12 Jan 2023 11:38:11 +0800 Message-ID: <20230112033811.58924-1-yangjihong1@huawei.com> X-Mailer: git-send-email 2.30.GIT MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.67.174.61] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemm600003.china.huawei.com (7.193.23.202) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" In literal sense of "max_samples_per_tick", if hwc->interrupts =3D=3D max_samples_per_tick, it should not be throttled, therefore, the judgment condition should be changed to "hwc->interrupts > max_samples_per_tick". In fact, this may cause the hardlockup to fail, The minimum value of max_samples_per_tick may be 1, in this case, the return value of __perf_event_account_interrupt function is 1. As a result, nmi_watchdog gets throttled, which would stop PMU (Use x86 architecture as an example, see x86_pmu_handle_irq). Signed-off-by: Yang Jihong --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index d56328e5080e..ced98e028d86 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -9414,7 +9414,7 @@ __perf_event_account_interrupt(struct perf_event *eve= nt, int throttle) } else { hwc->interrupts++; if (unlikely(throttle - && hwc->interrupts >=3D max_samples_per_tick)) { + && hwc->interrupts > max_samples_per_tick)) { __this_cpu_inc(perf_throttled_count); tick_dep_set_cpu(smp_processor_id(), TICK_DEP_BIT_PERF_EVENTS); hwc->interrupts =3D MAX_INTERRUPTS; --=20 2.30.GIT