Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754487Ab1BVQVE (ORCPT ); Tue, 22 Feb 2011 11:21:04 -0500 Received: from gate.lvk.cs.msu.su ([158.250.17.1]:46361 "EHLO mail.lvk.cs.msu.su" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753449Ab1BVQVB (ORCPT ); Tue, 22 Feb 2011 11:21:01 -0500 X-Spam-ASN: Date: Tue, 22 Feb 2011 19:20:52 +0300 From: Alexander Gordeev To: john stultz Cc: Thomas Gleixner , LKML , Rodolfo Giometti , Andrew Morton , Ingo Molnar Subject: Re: [PATCH] pps: Make pps_gen_parport depend on BROKEN Message-ID: <20110222192052.60039749@desktopvm.lvknet> In-Reply-To: <1298064881.2431.3.camel@work-vm> References: <1298064881.2431.3.camel@work-vm> Organization: LVK X-Mailer: Claws Mail 3.7.6 (GTK+ 2.20.1; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA256; boundary="Sig_/Ukatl1=BdzZ1jHJYttZTBRr"; protocol="application/pgp-signature" X-AV-Checked: ClamAV using ClamSMTP Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1902 Lines: 50 --Sig_/Ukatl1=BdzZ1jHJYttZTBRr Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Hi John, =D0=92 Fri, 18 Feb 2011 13:34:41 -0800 john stultz =D0=BF=D0=B8=D1=88=D0=B5=D1=82: > On Fri, 2011-02-18 at 22:16 +0100, Thomas Gleixner wrote: > > This driver causes hard lockups, when the active clock soure is > > jiffies. The reason is that it loops with interrupts disabled waiting > > for a timestamp to be reached by polling getnstimeofday(). Though with > > a jiffies clocksource, when that code runs on the same CPU which is > > responsible for updating jiffies, then we loop in circles for ever > > simply because the timer interrupt cannot update jiffies. So both UP > > and SMP can be affected. >=20 > Yuck. >=20 > Alexander, Rodolfo: Instead of polling on gtod, could you take a > timestamp, calculate the delay and then use udelay()? Sure, it's possible but it would be less precise IMHO. I'll test it. --=20 Alexander --Sig_/Ukatl1=BdzZ1jHJYttZTBRr Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) iQEcBAEBCAAGBQJNY+JkAAoJEElrwznyooJbO1oH/RRo1L+63VaqUvfUNa1j3qCC T/MXOy0z42m8AtRRfpfzZyWgPlnSOctML1dwgEO3udtc7jOEqJemYRILGnxU9OmS gbuvrdjQdKvnb9StEbJIgGJVCaridqbq+xLuzGbe9hxadDwl+u+S3dJltT0AXh6B W+jcVHSqdVrwqm6f+58tYCgWoNCznP88skfu+dg6GcXJWvHCCQXIrsh27I87YAkB G2jywdQaPI2JH0PTfd6q7Ro9RazPMrqv5jp9X8TRaPhtKJAm1Rrk+ZCwtdzb1P4c K+Nm4P0KRN0yc1AJosOMXuxdvkGfn8PfnH04EylQL2a8TrCom4IkThz9jpQc6ls= =/oE8 -----END PGP SIGNATURE----- --Sig_/Ukatl1=BdzZ1jHJYttZTBRr-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/