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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 87AA3C433F5 for ; Mon, 10 Jan 2022 16:52:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:To:Subject:Message-ID:Date:From: MIME-Version:Reply-To:Cc:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To: References:List-Owner; bh=zXgHN9/pOpRaIONgRiTUUbstHHxrlzrTIwHmujYwew4=; b=oGZ B2ao/ixdUb7hQoMySwbW8v+TBsgfpY/Y3jUSEvmI8cMZsqQ7zpjqTqrJQqNQ2HcjY4W2Md1uOjMWO FqaP1grerr0Ye9hSipxLcd07WcDNaKGVNarh4CfAOUlAPsfGd9yPgMSc4krjEZjkDkRycJRS/Sxen HPCuQIBcb9T3B+djc+WKT3o/a20d4JplyzjsQCwwih8iqYQ3a2xUsBK1QfPcNtoO/S8O0uQgr/e/i q1qN0ZrxLrMrXpC0LjASkkYu4c7mazlBQRJTSOAKfG3JMpAr8tBaAoqIbBV4EcWZs+zq8P101JWv1 36c1p3wWY/znhUsfLVa54lMw+seXd8A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1n6xtM-00CQRR-A9; Mon, 10 Jan 2022 16:51:32 +0000 Received: from mail-qk1-x730.google.com ([2607:f8b0:4864:20::730]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1n6xtJ-00CQQ9-0t for linux-arm-kernel@lists.infradead.org; Mon, 10 Jan 2022 16:51:30 +0000 Received: by mail-qk1-x730.google.com with SMTP id 69so15434106qkd.6 for ; Mon, 10 Jan 2022 08:51:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:from:date:message-id:subject:to; bh=5YcjYgKSCiZA3+wgXEeh3ApOxA8jCDKxwkajV4VfhU4=; b=EfYE5BgAhLm3pChd6L5pRmLl7YgamXQajJqtJGWa9yF+cl3SVXRbyOCpJKftfIyrnn UGZLA8hEW9L/hT/ziF+Cw/9c7VDCVGP40qEzKsMLM+l3pdkX20E3vw+zDNZ98uU4kuWT aiHx+uuJEIS3ULTdV4EDUF+vZ37iEvSPwHG6F4yHM1XbzM6DHU2dq3BFdvrqr4IjacM6 Ffxb3eKjMNjXWgW/GPc5M7hq2dzmUmsoaZQcKhlmQjotQEmhM25gW/SyuK2qpAoYrPrG 9eBMtDy4Qk50CrtDa0cMmzrI/Vp0KL/PUcIXysqn+j3js4QKTs/hXvsvqpvLg8+qmQEL vf9A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=5YcjYgKSCiZA3+wgXEeh3ApOxA8jCDKxwkajV4VfhU4=; b=ZAq3IMUcLdSJVZf5R/elIWHajaC6onDCALtA9+pG0dB8Ouu3mjRtXX/OWxviyEc0kH 4EMQmrzhspkCivwsTWjdFhM8XydeKT6AvjgISuMM1b9IHeJO7puuDJoBpuuYwD0Xbcac /6gaPOev3Jl0j4b4pLxqE3EBR2sgn5li5m8auzbePQ0mFAZmcCw/R5bi3tp29JmsNvh1 RAFjTmITeKLqubMLieJrUSh0uHfKX5kFIJ8UUahXamI3kuziRigz5u/uIZzbauA36A4U O0LSlfFqyRPQ1ddFKZioId5YTlqMM3kPNbcETx2iXwi0PNCVwTyWjojTvM/O1fg5LeYX QqBg== X-Gm-Message-State: AOAM533fmTo/j4QxNRKQPtehNbfWE6OnG1d46R5TpN1q90X1QoXcsqmV 6fiGDKQhw/zD3Plfy0g23aemGtpG+hwnifLpO5CwrcaPYQVwYw== X-Google-Smtp-Source: ABdhPJyttqQhosIqLLtoJnWjs7Eg25urpjZykkeJHDF7/XLKrZvor4tx4WLN1mVlJCwqOHBa7g0usRJzSBv/mwxOurU= X-Received: by 2002:a37:668a:: with SMTP id a132mr422683qkc.460.1641833485447; Mon, 10 Jan 2022 08:51:25 -0800 (PST) MIME-Version: 1.0 From: Huichun Feng Date: Tue, 11 Jan 2022 00:51:14 +0800 Message-ID: Subject: Does clocksource arch_sys_counter synchronize across CPUs? To: linux-arm-kernel@lists.infradead.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220110_085129_102461_1AEC63E3 X-CRM114-Status: UNSURE ( 5.62 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi list, AFAIK, one of the clocksource in arm64 (armv8.3, Rpi4) -- arch_sys_counter, uses a per-core register CNTVCT as the accessor. And comes to consistency of CNTVCT's, after searching some of the related manuals [0-2], I didn't find statements saying that it is synchronize across CPUs. However, I've found a recent patch [3] says that CNTVCT is synchronized in armv8.6. So, does CNTVCT synchronize across CPUs in armv8.3? thanks. Huichun [0] https://datasheets.raspberrypi.com/bcm2711/bcm2711-peripherals.pdf [1] https://developer.arm.com/documentation/den0024/a/ARMv8-Registers/System-registers [2] https://developer.arm.com/documentation/102379/0000/The-processor-timers?lang=en [3] https://www.spinics.net/lists/arm-kernel/msg934605.html _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel