From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752370AbeB1MDM (ORCPT ); Wed, 28 Feb 2018 07:03:12 -0500 Received: from mga14.intel.com ([192.55.52.115]:8055 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752195AbeB1MDL (ORCPT ); Wed, 28 Feb 2018 07:03:11 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.47,405,1515484800"; d="asc'?scan'208";a="38105551" From: Felipe Balbi To: Thomas Gleixner Cc: Alessandro Zummo , Alexandre Belloni , linux-kernel@vger.kernel.org, linux-rtc@vger.kernel.org Subject: Re: HRTimer causing rtctest to fail In-Reply-To: References: <87vaei601x.fsf@linux.intel.com> <87muzt5usg.fsf@linux.intel.com> <87k1ux5qpf.fsf@linux.intel.com> Date: Wed, 28 Feb 2018 14:02:20 +0200 Message-ID: <87h8q15nlf.fsf@linux.intel.com> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Hi, Thomas Gleixner writes: > On Wed, 28 Feb 2018, Felipe Balbi wrote: >> Thomas Gleixner writes: >> > All numbers in micro seconds! What happens if you load the system or >> > restrict C-States? >>=20 >> added intel_idle.max_cstate=3D0 to cmdline. Still see some failures, >> albeit a lot more rare, for example, caught one on iteration 8 of >> 8192Hz: >>=20 >> 8192Hz: 1 2 3 4 5 6 7 >> PIE delta error: 0.000135 should be close to 0.000122 >>=20 >> That is, however, only 13 uS late. Is that within the limits of "we >> don't quite care"? > > I think so. 13us (depending on the machine) can easily happen if multiple > interrupts/timers happen at the same time or if something keeps interrupts > disabled for a few microseconds which is certainly possible. > > What kind of system is this? 4 core Kabylake. >> BTW, it took some effort to get that one failure. I'll leave rtctest >> running in a long loop and try to figure out approximately how frequently >> it fails, but it seems like it's within the realm of "don't care", would >> you agree? > > Yes. cool, thanks =2D-=20 balbi --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEElLzh7wn96CXwjh2IzL64meEamQYFAlqWmkwACgkQzL64meEa mQb/ew/9Gnyi62Ax+VhMMlisM+4JJVP2AqY+MM9c7KMs/TwdNEaUwBhdkIE2gd4L jb+x9RdKRL8cpx3dZkzrhXSRvOfOfL7EXNjL2rUJkX/R+PUSkP1yMH0P90CqmMmD awGBxmveQ6/Dwg+jcSR0nRhbShLfY8Q36nRESHUQtTCBDweNcQTB7qFyDsF3/KHY 476+lpNVWc8thm7yxATZN8epGU9SbhI39pmnzyrPnEOPCOi7Gf+qit/AHOtYB7x2 kUZRVqHeOdnBAFMwTxV+syWKNsIE/lA5Km3wf+d0bubDhAHsBZvLj1JBslkxY5lf in0yrsFLmKHJYJBvctRbGQuRwf1yY7LWFFD07spjIIDHCK8dBn1wdC2jq0a90tM6 a+SIjL+YryOKF0kPR85y4JJYKUq4XcIw9VXqkcFaYt4fgQ9TCwpI7hZfv+5Vys3W QegfxWWIqaMpnAIwnJEf63+4qj2pzlX2n7fMK/ZlU/pOVmFXvYEJSLbuUFcdgcIK 7WznEQgbCW8lfzhScjqswvWPSrf1R6KuYo8vRAYFMxccCKSiRfbC84Te6xqcq8WQ Bu/UL+v/f97jV0vpnv7dqv07Di+C48PWY9aUoImV6EvNI+X0g/sKQEhaxBR4I5Ab up8RR+W0kOEB9sN3KN4CyIOmCioLZ6oVFTW7QzyM7QLZzq2K/4s= =dEkH -----END PGP SIGNATURE----- --=-=-=--