From patchwork Wed Jun 17 11:38:44 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexandru Elisei X-Patchwork-Id: 11609753 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4751313A0 for ; Wed, 17 Jun 2020 11:40:45 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 21D35207DD for ; Wed, 17 Jun 2020 11:40:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="st6CmGol" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 21D35207DD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:To :From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=Sc/XyvcG0P3vQd8DIHHy1gmCsxvFDfi+3w88hu7ipKM=; b=st6CmGolSbSd2F yhpbOutURqK/7a/rWhdFbSMQAS5Xsxfhj6ha2ORtZ0ZBLKhNLm/7bdTl7dmpL9C8CiYxRgP51dvCH nIZMHe+3JRGavIZjpMAo6CvoG37FUhwUp6GWF0Fbh3Tktd0GAlyJy3jcqHGyvHr2EXkZKvRUH0LMH gAUZwwl7zWzMClSKXrgO/Z9spTHojsZDu9d2k/qXEIOpbEH4iG1rwpo6kB+y5xHZ/y3Ehdk62w254 K4bSuSxWA/o0xYiVhj9eeuScwHH3/kyNXOxvFtC0ia4br3d44PeWQKJToh7Jhtupia10nU0pbocBE u3IsQCsIYEXtQya7zeuQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jlWQn-000583-If; Wed, 17 Jun 2020 11:40:37 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jlWOa-0001UT-Hm for linux-arm-kernel@lists.infradead.org; Wed, 17 Jun 2020 11:38:23 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 438A91042; Wed, 17 Jun 2020 04:38:18 -0700 (PDT) Received: from monolith.arm.com (unknown [10.37.8.7]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0CD143F71F; Wed, 17 Jun 2020 04:38:16 -0700 (PDT) From: Alexandru Elisei To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 0/7] arm_pmu: Use NMI for perf interrupt Date: Wed, 17 Jun 2020 12:38:44 +0100 Message-Id: <20200617113851.607706-1-alexandru.elisei@arm.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200617_043820_784546_3A37778E X-CRM114-Status: GOOD ( 14.27 ) X-Spam-Score: -2.3 (--) X-Spam-Report: SpamAssassin version 3.4.4 on bombadil.infradead.org summary: Content analysis details: (-2.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at https://www.dnswl.org/, medium trust [217.140.110.172 listed in list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, maz@kernel.org, will@kernel.org, catalin.marinas@arm.com Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org The series makes the arm_pmu driver use NMIs for the perf interrupt when NMIs are available on the platform (currently, only arm64 + GICv3). To make it easier to play with the patches, I've pushed a branch at [1]: $ git clone -b pmu-nmi-v5 git://linux-arm.org/linux-ae I've tested the series on an espressobin v7*. These are the results of running perf record -a -- sleep 60: 1. Without the patches: 12.68% [k] _raw_spin_unlock_irq 11.08% [k] arch_cpu_idle 7.86% [k] _raw_spin_unlock_irqrestore 6.05% [k] arch_counter_get_cntpct 2.86% [k] __softirqentry_text_start 2.33% [k] tick_nohz_idle_exit [..] 2. Using NMIs: 19.45% [k] arch_counter_get_cntpct 5.14% [k] __delay 3.32% [k] wait_for_xmitr 1.99% [k] ktime_get 1.00% [k] _raw_write_lock_irqsave 1.00% [.] avahi_escape_label [..] When running perf record -a -- iperf3 -c 127.0.0.1 -t 60: 1. Without the patches: 24.70% [k] __arch_copy_from_user 21.77% [k] __arch_copy_to_user 5.21% [k] _raw_spin_unlock_irq 2.86% [k] _raw_spin_unlock_irqrestore 1.99% [k] __free_pages_ok 1.61% [k] arch_cpu_idle [..] 2. Using NMIs: 23.84% [k] __arch_copy_from_user 23.44% [k] __arch_copy_to_user 1.23% [k] get_page_from_freelist 1.16% [k] tcp_ack 0.80% [k] __free_pages_ok 0.78% [k] tcp_sendmsg_locked [..] I've ran the same tests in a VM when both host+guest use NMIs, and when neither use them. All of these tests were also ran on the model. Similar results in all cases. * All the firmware versions for espressobin v7 that I've tried clear SCR_EL3.FIQ, which means that NMIs don't work. To make them work on the board, I modified the GICv3 driver. That's why I would really appreciate someone testing this series on a board where NMIs work without any GIC changes. Summary of the patches: * Patch 1 is a fix for a bug that Julien found during the review for v4. * Patches 2 and 3 remove locking from arm64 perf event code. * Patches 4 and 5 makes the arm64 PMU interrupt handler NMI safe. * Patches 6 and 7 enable the use of NMIs on arm64 with a GICv3 irqchip. Changes since v4 [2]: - Rebased on top of v5.8-rc1 and dropped the Tested-by tags because it's been almost a year since the series has been tested. - Dropped patch 3 because I couldn't find any instance where armv7pmu_read_counter() was called with interrupts enabled. I've also tested this by running several instances of perf for a few hours, and the function was called every time with interrupts disabled. - Dropped patches 4 and 5 because the tradeoff wasn't worth it in my opinion: the irq handler was slower all the time (because it saved/restored the counter select register), in exchange for being slightly faster on the rare ocassions when it triggered at the beginning of the critical sections. - Minor changes here and there to address review comments. Changes since v3 [3]: - Added tags - Fix build issue for perf_event_v6 - Don't disable preemption in pmu->enable() - Always rely on IPI_IRQ_WORK to run the queued work - Fixed typos + cleanups Changes since v2 [4]: - Rebased on recent linux-next (next-20190708) - Fixed a number of bugs with indices (reported by Wei) - Minor style fixes Changes since v1 [5]: - Rebased on v5.1-rc1 - Pseudo-NMI has changed a lot since then, use the (now merged) NMI API - Remove locking from armv7 perf_event - Use locking only in armv6 perf_event - Use direct counter/type registers insted of selector register for armv8 [1] http://www.linux-arm.org/git?p=linux-ae.git;a=shortlog;h=refs/heads/pmu-nmi-v5 [2] https://lists.infradead.org/pipermail/linux-arm-kernel/2019-July/666824.html [3] https://lists.infradead.org/pipermail/linux-arm-kernel/2019-July/665339.html [4] https://lists.infradead.org/pipermail/linux-arm-kernel/2019-March/640536.html [5] https://lists.infradead.org/pipermail/linux-arm-kernel/2018-January/554611.html Alexandru Elisei (1): arm64: perf: Add missing ISB in armv8pmu_enable_event() Julien Thierry (5): arm64: perf: Remove PMU locking arm64: perf: Defer irq_work to IPI_IRQ_WORK arm64: kvm: pmu: Make overflow handler NMI safe arm_pmu: Introduce pmu_irq_ops arm_pmu: arm64: Use NMIs for PMU Mark Rutland (1): arm64: perf: Avoid PMXEV* indirection arch/arm64/kernel/perf_event.c | 138 ++++++++++++++++++++------------ arch/arm64/kvm/pmu-emul.c | 25 +++++- drivers/perf/arm_pmu.c | 142 ++++++++++++++++++++++++++++----- include/kvm/arm_pmu.h | 1 + 4 files changed, 235 insertions(+), 71 deletions(-)