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 8C23CC2BB41 for ; Wed, 17 Aug 2022 21:57:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242443AbiHQV5y (ORCPT ); Wed, 17 Aug 2022 17:57:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60346 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241364AbiHQV5w (ORCPT ); Wed, 17 Aug 2022 17:57:52 -0400 Received: from matoro.tk (unknown [IPv6:2600:1700:4b10:9d80::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 65A21AA4F1 for ; Wed, 17 Aug 2022 14:57:48 -0700 (PDT) DKIM-Signature: a=rsa-sha256; bh=yOKakIqHXCzZv31j5+n9zOkk3z3d5d3Q9bnca8uv+no=; c=relaxed/relaxed; d=matoro.tk; h=Subject:Subject:Sender:To:To:Cc:Cc:From:From:Date:Date:MIME-Version:MIME-Version:Content-Type:Content-Type:Content-Transfer-Encoding:Content-Transfer-Encoding:Reply-To:In-Reply-To:In-Reply-To:Message-Id:Message-Id:References:References:Autocrypt:Openpgp; i=@matoro.tk; s=20220801; t=1660773462; v=1; x=1661205462; b=waa3nn9Z2IABkYVlk43UMeRg1lCDp8Q/4glQ4TphrDMLmVlvG585ve+f0GMnVeN4mXiu+Qjo O7PcvN0STCnkmupFzGFM9ZIsfW5GYZ92NsEf5GXEQyTHv8LgcPNR7XeSxnVGQKeDoW+uq6L3+1y 5OR2/BTABjVv/lAf7sKfSFd+RNZuK04WfDKL0QxGWFbibKR334HY5eqF+PTH6V7mlHDraJCNYh6 lX6l4NO/6a1qMALhfRFhSEY4DeuSSATU+41uQOd8zoCdIYS+0mTzVquYa3ybUTkab3AWAvvyISu iwEJrgOJ3GTeskHFZFi4AIaZnFc1j5NAFeU3DHwzjM7RxadByveQ5WXsNXlM12cwBXlsQOCj/qf 6cXI7QmqDrqZ969UE4LTvngOswSNfQJneuQiC/OHnGoZ8005bgz0QY9tK6oM6mCX22pKT8imD6j XBaEKnF98Lfxemu4AHhtfr10JFR8HHdzTm9f8YqHEB4CAxXnitjn6yvZlYr1BO7B8LIDm6/CS0j rSInf2lg7KtFm4ne04qNDiXLJHfpRraYeMXNxPs1MNlrj43lNDrrtHBJUBU/iXaql8cXrVWS2wT TTmtyr45bc6G3j3YYM5BI2KFzKTRbPFuwSjFzTKA/urCUVwYBJOOpkzVLPOlxQjSIQwAl5OGBYN tuIbcrx0ubo= Received: by matoro.tk (envelope-sender ) with ESMTPS id 80adfee9; Wed, 17 Aug 2022 17:57:42 -0400 MIME-Version: 1.0 Date: Wed, 17 Aug 2022 17:57:42 -0400 From: matoro To: Andrew Morton Cc: Sergei Trofimovich , linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org Subject: Re: [PATCH] ia64: fix clock_getre(CLOCK_MONOTONIC) to report ITC frequency In-Reply-To: <20220817122103.ecbd08bd545385e5bf8e0d72@linux-foundation.org> References: <20220815054944.4130786-1-slyich@gmail.com> <20220817122103.ecbd08bd545385e5bf8e0d72@linux-foundation.org> Message-ID: <6d07209d000b671a3bc48003905652e8@matoro.tk> X-Sender: matoro_mailinglist_kernel@matoro.tk Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Andrew, I came up with the prototype for this patch, but it was based entirely on Sergei's investigation which was documented in https://bugs.gentoo.org/596382. I asked him to send it upstream because I'm unable to attach my realname to it due to my job. I can place a signed-off-by with my handle but I understand that's normally against kernel policy which is why I didn't. Either way the bulk of the work belongs to Sergei, I just scribbled it down, and he cleaned it up for this submission. -------- Original Message -------- Subject: Re: [PATCH] ia64: fix clock_getre(CLOCK_MONOTONIC) to report ITC frequency Date: 2022-08-17 15:21 From: Andrew Morton To: Sergei Trofimovich On Mon, 15 Aug 2022 06:49:44 +0100 Sergei Trofimovich wrote: > clock_gettime(CLOCK_MONOTONIC, &tp) is very precise on ia64 as it uses > ITC (similar to rdtsc on x86). It's not quite a hrtimer as it is a few > times slower than 1ns. Usually 2-3ns. > > clock_getres(CLOCK_MONOTONIC, &res) never reflected that fact and > reported 0.04s precision (1/HZ value). > > In https://bugs.gentoo.org/596382 gstreamer's test suite failed loudly > when it noticed precision discrepancy. > > Before the change: > > clock_getres(CLOCK_MONOTONIC, &res) reported 250Hz precision. > > After the change: > > clock_getres(CLOCK_MONOTONIC, &res) reports ITC (400Mhz) precision. > > The patch is based on matoro's fix. It adds a bit of explanation why we > need to special-case arch-specific clock_getres(). > It would be best (and nice) to include the original developer's Signed-off-by: and to Cc Émeric Maschino if possible? Could you please take care of these paperwork issues? From mboxrd@z Thu Jan 1 00:00:00 1970 From: matoro Date: Wed, 17 Aug 2022 21:57:42 +0000 Subject: Re: [PATCH] ia64: fix clock_getre(CLOCK_MONOTONIC) to report ITC frequency Message-Id: <6d07209d000b671a3bc48003905652e8@matoro.tk> List-Id: References: <20220815054944.4130786-1-slyich@gmail.com> <20220817122103.ecbd08bd545385e5bf8e0d72@linux-foundation.org> In-Reply-To: <20220817122103.ecbd08bd545385e5bf8e0d72@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable To: Andrew Morton Cc: Sergei Trofimovich , linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org Hi Andrew, I came up with the prototype for this patch, but it was based=20 entirely on Sergei's investigation which was documented in=20 https://bugs.gentoo.org/596382. I asked him to send it upstream because=20 I'm unable to attach my realname to it due to my job. I can place a=20 signed-off-by with my handle but I understand that's normally against=20 kernel policy which is why I didn't. Either way the bulk of the work=20 belongs to Sergei, I just scribbled it down, and he cleaned it up for=20 this submission. -------- Original Message -------- Subject: Re: [PATCH] ia64: fix clock_getre(CLOCK_MONOTONIC) to report=20 ITC frequency Date: 2022-08-17 15:21 From: Andrew Morton To: Sergei Trofimovich On Mon, 15 Aug 2022 06:49:44 +0100 Sergei Trofimovich =20 wrote: > clock_gettime(CLOCK_MONOTONIC, &tp) is very precise on ia64 as it uses > ITC (similar to rdtsc on x86). It's not quite a hrtimer as it is a few > times slower than 1ns. Usually 2-3ns. >=20 > clock_getres(CLOCK_MONOTONIC, &res) never reflected that fact and > reported 0.04s precision (1/HZ value). >=20 > In https://bugs.gentoo.org/596382 gstreamer's test suite failed loudly > when it noticed precision discrepancy. >=20 > Before the change: >=20 > clock_getres(CLOCK_MONOTONIC, &res) reported 250Hz precision. >=20 > After the change: >=20 > clock_getres(CLOCK_MONOTONIC, &res) reports ITC (400Mhz) precision. >=20 > The patch is based on matoro's fix. It adds a bit of explanation why we > need to special-case arch-specific clock_getres(). >=20 It would be best (and nice) to include the original developer's Signed-off-by: and to Cc =C3=89meric Maschino if possible? Could you please take care of these paperwork issues?