From owner-freebsd-arch@FreeBSD.ORG Tue Nov 25 08:58:51 2014 Return-Path: Delivered-To: arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id B3E321CE; Tue, 25 Nov 2014 08:58:51 +0000 (UTC) Received: from gromit.grondar.org (grandfather.grondar.org [IPv6:2a01:348:0:15:5d59:5c20:0:2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 73736783; Tue, 25 Nov 2014 08:58:51 +0000 (UTC) Received: from [2001:470:9174:1:a022:fe58:8d38:bb1f] by gromit.grondar.org with esmtpsa (TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.84 (FreeBSD)) (envelope-from ) id 1XtBxP-0003Mi-2n; Tue, 25 Nov 2014 08:58:48 +0000 Subject: Re: svn commit: r274739 - head/sys/mips/conf Mime-Version: 1.0 (Mac OS X Mail 8.1 \(1993\)) Content-Type: text/plain; charset=utf-8 From: Mark R V Murray In-Reply-To: <8661e3wtk6.fsf@nine.des.no> Date: Tue, 25 Nov 2014 08:58:45 +0000 Content-Transfer-Encoding: quoted-printable Message-Id: References: <201411200552.sAK5qnXP063073@svn.freebsd.org> <20141120084832.GE24601@funkthat.com> <20141121092245.GI99957@funkthat.com> <1416582989.1147.250.camel@revolution.hippie.lan> <026FEB8A-CA8C-472F-A8E4-DA3D0AC44B34@grondar.org> <1416596266.1147.290.camel@revolution.hippie.lan> <1416598889.1147.297.camel@revolution.hippie.lan> <86egsvueqk.fsf@nine.des.no> <1416691274.1147.339.camel@revolution.hippie.lan> <398A380D-49AF-480C-8842-8835F81EF641@grondar.org> <1416806894.1147.362.camel@revolution.hippie.lan> <18B8A926-59C0-49B4-ADA3-A11688609852@grondar.org> <1416841268.1147.386.camel@revolution.hippie.lan> <86wq6k9okk.fsf@nine.des.no> <8661e3wtk6.fsf@nine.des.no> To: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= X-Mailer: Apple Mail (2.1993) X-SA-Score: -1.0 Cc: arch@freebsd.org, Ian Lepore X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 25 Nov 2014 08:58:51 -0000 > On 25 Nov 2014, at 08:52, Dag-Erling Sm=C3=B8rgrav wrote: >=20 > Mark R V Murray writes: >> How two consecutive calls to get_cyclecount() can repeatedly return >> such massive numbers is an indication that something has gone badly >> wrong. >=20 > No, wait. I looked at the code. The most likely explanation is that = it > is falling through to this: >=20 > binuptime(&bt); > return ((uint64_t)bt.sec << 56 | bt.frac >> 8); >=20 > so the top 8 bits are seconds (meaning that get_cyclecount wraps = around > every 256 seconds) and the bottom 64 are the base 2 fractional part. = At > first glance, Ian's number seem to be identical from one run to the > next, but they're not - there seems to be a small amount of variation. > But I'm still very suspicious of at91_st0, which is constant, and > nexus0, at91_aic0 and at91_pmc0, which are constant *and* identical. Ian - could you please print the 2 get_cyclecount() return values as = well as the difference on that same hardware and at the same place as = you did you previous change? Thanks. M --=20 Mark R V Murray