From mboxrd@z Thu Jan 1 00:00:00 1970 From: Miroslav Lichvar Subject: Re: [PATCH] igb: shorten maximum PHC timecounter update interval Date: Fri, 26 Oct 2018 14:04:16 +0200 Message-ID: <20181026120416.GB27139@localhost> References: <20181012111339.1361-1-mlichvar@redhat.com> <20181012140530.6mjxkb2co3nhl5pf@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org, Jacob Keller , Thomas Gleixner To: Richard Cochran Return-path: Received: from mx1.redhat.com ([209.132.183.28]:59686 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727491AbeJZUlJ (ORCPT ); Fri, 26 Oct 2018 16:41:09 -0400 Content-Disposition: inline In-Reply-To: <20181012140530.6mjxkb2co3nhl5pf@localhost> Sender: netdev-owner@vger.kernel.org List-ID: On Fri, Oct 12, 2018 at 07:05:30AM -0700, Richard Cochran wrote: > On Fri, Oct 12, 2018 at 01:13:39PM +0200, Miroslav Lichvar wrote: > > Since commit 500462a9d ("timers: Switch to a non-cascading wheel"), > > scheduling of delayed work seems to be less accurate and a requested > > delay of 540 seconds may actually be longer than 550 seconds. Shorten > > the delay to 480 seconds to be sure the timecounter is updated in time. > > Good catch. This timer wheel change will affect other, similar > drivers. Guess I'll go through and adjust their timeouts, too. I just realized that we need to fit there also any frequency adjustments of the PHC and system clock. The PHC can be set to run up to 6% faster and the system clock can be slowed down by up to 10%. Those 480 seconds in the igb driver is not short enough for that. Should I fix and resend this patch, or send a new one? Other drivers may have a similar problem. -- Miroslav Lichvar