From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joanna Rutkowska Subject: Re: dom0 is stalled until a keypress Date: Wed, 07 Sep 2011 11:03:13 +0200 Message-ID: <4E673351.6060206@invisiblethingslab.com> References: <20110905091937.GA1906@email> <36a5b662-4420-41aa-be01-445f83b15a7b@default 4E664BEE.9000208@invisiblethingslab.com> <71fba00b-9a7a-4029-ac11-4d37732bb53f@default> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0347598744==" Return-path: In-Reply-To: <71fba00b-9a7a-4029-ac11-4d37732bb53f@default> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Dan Magenheimer Cc: xen-devel@lists.xensource.com, Rafal Wojtczuk List-Id: xen-devel@lists.xenproject.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --===============0347598744== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigF38E68AB495573FBA3C5C4CE" This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigF38E68AB495573FBA3C5C4CE Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 09/06/11 19:17, Dan Magenheimer wrote: >> From: Joanna Rutkowska [mailto:joanna@invisiblethingslab.com] >> Subject: Re: [Xen-devel] dom0 is stalled until a keypress >> >> On 09/06/11 17:49, Dan Magenheimer wrote: >>>> From: Rafal Wojtczuk [mailto:rafal@invisiblethingslab.com] >>>> Sent: Monday, September 05, 2011 3:20 AM >>>> To: xen-devel@lists.xensource.com >>>> Subject: [Xen-devel] dom0 is stalled until a keypress >>>> >>>> Hello, >>>> The following bizarre behaviour was observed on xen4.1+suse dom0 2.6= =2E38, on >>>> an old Core Duo laptop; maybe someone can hint what is wrong. >>>> Dom0 boot stalls after an init.d script prints "Starting udev". Then= nothing >>>> seems to happen. I need to press any key to observe progress - I nee= d to do >>>> it tens of times for the boot to finish. After X starts fine, then t= here is >>>> no need for keypressing anymore. >>>> A particularly disturbing fact is that qrexec_daemon parent, that ba= sically >>>> does >>>> for (;;) { sleep(1); fprintf(stderr, "."); } >>>> does not print dots, until a keypress arrives. So something is very = wrong >>>> with timers. >>>> Somehow similarly, pm-suspend sometimes hangs at some stage - after = detaching >>>> power cord, machine enters S3 immediately. >>>> This is vaguely similar to the issue described in >>>> https://lkml.org/lkml/2008/9/14/122 >>>> but this time, "nohz=3Doff" does not help. >>>> >>>> "cpufreq=3Ddom0-kernel" cures the symptoms; but it is not a sideeffe= ctless >>>> solution. Any idea what is going on or how to debug it ? >>> >>> ISTR seeing this on a Core(2?)Duo laptop and I think the >>> workaround was setting max_cstate=3D0 (as Xen boot parameter). >>> >> But what was the actual problem? Setting max_cstate is probably even >> worse for power management than setting cpufreq=3Ddom-kernel, isn't it= ? >=20 > Sorry, dunno. I recall looking into it a bit and finding that > the Core processor (and possibly specifically Merom, the laptop > version) had some special C-state (C3, C1E maybe?) and giving > up at that point. Sorry I can't be more helpful. But the same system worked fine without any tweaks (cpufreq, max_cstate) on Xen 3.4 and only started exhibiting this behavior after we switched to Xen 4.1... j. --------------enigF38E68AB495573FBA3C5C4CE Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/ iQEcBAEBAgAGBQJOZzNSAAoJEDaIqHeRBUM02nsH/0/kZg0wCi7w+TdGqYEnA+k8 5KQfvdDUidWs7tGEIHAVoYp64uJlWRnWXoWfKE8Q39cBtnQ8/QCnUGyV+0S3OY+C QR/8Q8cy9p1vVCUJp8Wz5IGg6WP/oTUlrBNFwmCwOkeW9/+ypEeDi9CUBczcM4n+ 5Ew/49jmyaISpy2XPLCdn8rbbSgnR3OHNatVI/Sxq8d+KUhJy4tgUnmKiQ2oB/rD 9z77CV4v1qQ6SzEMQBSjR3bEzAxAIblhDJvTRt1TdxYXprVizN/GjPzYbsMGaeGa x1jJys4+8crqjyPkuzXSbCwg1MYM+FALXyAp+mogb+pOxRj2BZDDfGWHPoL/eEk= =OJBZ -----END PGP SIGNATURE----- --------------enigF38E68AB495573FBA3C5C4CE-- --===============0347598744== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel --===============0347598744==--