Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752114AbdCDJfw (ORCPT ); Sat, 4 Mar 2017 04:35:52 -0500 Received: from off.redlab-i.ru ([195.16.34.157]:42366 "EHLO mail.gerasiov.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750769AbdCDJfu (ORCPT ); Sat, 4 Mar 2017 04:35:50 -0500 X-Greylist: delayed 917 seconds by postgrey-1.27 at vger.kernel.org; Sat, 04 Mar 2017 04:35:50 EST X-Spam-ASN: Date: Sat, 4 Mar 2017 12:19:45 +0300 From: Alexander Gerasiov To: Rodolfo Giometti Cc: Andrey Drobyshev , linux-kernel@vger.kernel.org, Thomas Gleixner Subject: Re: [PATCH 8/8] LinuxPPS: pps_gen_parport: Add check for bad clocksource. Message-ID: <20170304121945.06e7bbfd@brick.gerasiov.net> In-Reply-To: References: <1487169069-15721-1-git-send-email-immortalguardian1@gmail.com> <1487169069-15721-9-git-send-email-immortalguardian1@gmail.com> X-Mailer: Claws Mail 3.14.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1573 Lines: 43 Hello Rodolfo, I should say, that I found this solution is not the best. For example on high speed PCs (I think over 3GHz) 5 iteration is not enough and module stops working after several hours. That makes it not user-friendly, cause user had to calibrate and set failure_iterations manually. It would be better to use pre-measured loops_per_jiffy (from delay.h) some way. On Sat, 4 Mar 2017 08:44:03 +0100 Rodolfo Giometti wrote: > On 02/15/17 15:31, Andrey Drobyshev wrote: > > From: Nikita Edward Baruzdin > > > > This commit is supposed to resolve the issue with hard lockups on > > systems using jiffies as their clock source. Namely, it sets limits > > on number of iterations clock source may remain unchanged (i. e. > > not being updated for one reason or another, as it is with jiffies > > clock source), and on unsuccessful getnstimeofday() polls as well. > > In case limit is reached, we consider clock source incompatible > > with this driver or unstable. > > > > Considering this issue to be fixed, un-BROKEN pps_gen_parport. > > > > For explanation of the problem see this thread on lkml: > > https://lkml.org/lkml/2011/2/18/310 > > > > Signed-off-by: Nikita Edward Baruzdin > > Signed-off-by: Alexander GQ Gerasiov > > Acked-by: Rodolfo Giometti -- Best regards, Alexander Gerasiov Contacts: e-mail: gq@cs.msu.su Homepage: http://gerasiov.net Skype: gerasiov PGP fingerprint: 04B5 9D90 DF7C C2AB CD49 BAEA CA87 E9E8 2AAC 33F1