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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2EDC4C433EF for ; Tue, 26 Apr 2022 20:39:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355106AbiDZUmR (ORCPT ); Tue, 26 Apr 2022 16:42:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38892 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355032AbiDZUmE (ORCPT ); Tue, 26 Apr 2022 16:42:04 -0400 Received: from mail-vs1-xe33.google.com (mail-vs1-xe33.google.com [IPv6:2607:f8b0:4864:20::e33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9D4B9793AC for ; Tue, 26 Apr 2022 13:38:53 -0700 (PDT) Received: by mail-vs1-xe33.google.com with SMTP id q2so4759226vsr.5 for ; Tue, 26 Apr 2022 13:38:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=wfJd9A+0QWj9RbTol5Rw0Pj2t6CVgO2Un6yqTZKi1SM=; b=qqHQRi4aq2NvDCTC+RiF4zAZv3IsuwZr1Iaa5zU57qyOcygb47zXA8qkTO21xszuU0 DUyEcSl3HgZsFVc1dLZFm1kLBdjg6kekUw12ZE6YIh/t17+vu6g1JZe0ktZkHO4Rh5M5 PSe8TMaQyukTdBYuRJ2voBBujTxxWS5utDDRGMzn3W8WgKv6Pyz0nJgn82WLrsNCgATT 5QRrBsy/aqRYINdJ/40KJiqjR4E7emxXpqnmJ6bgPsVw2I4n47Y7NOUuurA4paMU65oz BNfA5DOykIeCvJRIbfU+5/PozOjpomLmkyppl9SUBFcH8fG9lMgN+5Iu2vmJYnQlzRHV 3KYg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=wfJd9A+0QWj9RbTol5Rw0Pj2t6CVgO2Un6yqTZKi1SM=; b=rg/zp522oKNtigkTdkSXNL4wenpo3hqgyzuhM2rEFhrtyiN0SP8rAd37qe0hsDDbh5 yA70of1Mti5ECHQAuvXxLpEtk4P8aRIBbyKvAuaXGDXOS5P8AIsD3GU53iKkR9iCWR9q exECIrRsU7YWSNDdBgXYMe09+6L62gVc53Mv9OxrOGRz5Gkx/Efh/C5C33oKT/82t90W nFJloKx+XPhjkMoDsDzDTiah7d/wVMqTb7Apq4WzsZE/ENRIF4AtGOpd979l8L3PxZ6u 9HcKVIEeSXvxJbrm4+myJQnMyJEj/RgYNaztcEjZQis1IayJIMoARy458XGkbdkakm28 /1nA== X-Gm-Message-State: AOAM531ci+sqWgkcyWTdGYo9tOhjRx/8fb8ZrXpX+sDCbm5bB8iT1yV9 glgndRnK+1g7dT4uK3pXwOlhusgDIzTB2taJxKit X-Google-Smtp-Source: ABdhPJwQkHaUU9ii+vNTdfepYExsOc2JJHBLTd8X+78D6DqxnogbZcYYM3kPozNJ7Yj9xC1ycRgHRnkSP4GdagdGExg= X-Received: by 2002:a67:eb86:0:b0:32c:2036:17fe with SMTP id e6-20020a67eb86000000b0032c203617femr8013131vso.47.1651005532543; Tue, 26 Apr 2022 13:38:52 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: John Stultz Date: Tue, 26 Apr 2022 13:38:40 -0700 Message-ID: Subject: Re: [PATCH 1/3] sched_clock: Round the frequency reported to nearest rather than down To: "Maciej W. Rozycki" Cc: Thomas Gleixner , Stephen Boyd , Russell King , Ingo Molnar , linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Apr 24, 2022 at 4:47 AM Maciej W. Rozycki wrote: > > We currently round the frequency reported for clock sources down, which > gives misleading figures, e.g.: > > I/O ASIC clock frequency 24999480Hz > clocksource: dec-ioasic: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 76452008078 ns > sched_clock: 32 bits at 24MHz, resolution 40ns, wraps every 85901132779ns > MIPS counter frequency 59998512Hz > clocksource: MIPS: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 31855130776 ns > sched_clock: 32 bits at 59MHz, resolution 16ns, wraps every 35792281591ns > > Rounding to nearest seems more adequate: > > I/O ASIC clock frequency 24999664Hz > clocksource: dec-ioasic: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 76451445358 ns > sched_clock: 32 bits at 25MHz, resolution 40ns, wraps every 85900499947ns > MIPS counter frequency 59999728Hz > clocksource: MIPS: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 31854485176 ns > sched_clock: 32 bits at 60MHz, resolution 16ns, wraps every 35791556599ns > > Signed-off-by: Maciej W. Rozycki > Fixes: 112f38a4a316 ("ARM: sched_clock: provide common infrastructure for sched_clock()") > --- This seems sane to me. Acked-by: John Stultz thanks -john