From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joanna Rutkowska Subject: Re: A clocksource question Date: Fri, 12 Mar 2010 01:38:01 +0100 Message-ID: <4B998CE9.2030704@invisiblethingslab.com> References: <4B962748.90609@invisiblethingslab.com> <4B96DB69.10101@goop.org 4B981997.4030605@invisiblethingslab.com> <56cc3abf-21f6-4178-b00e-0331538080d9@default> <4FA716B1526C7C4DB0375C6DADBC4EA3554D53F1B0@LONPMAILBOX01.citrite.net> <4B983EC9.2030105@invisiblethingslab.com> <4B98421F.7040102@goop.org> <4B984533.9030402@invisiblethingslab.com> <4B9877CA.4060204@goop.org> <4B998A70.3050500@invisiblethingslab.com> <4B998F9A.3040706@goop.org> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============2127628285==" Return-path: In-Reply-To: <4B998F9A.3040706@goop.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Jeremy Fitzhardinge Cc: Ian Pratt , "xen-devel@lists.xensource.com" , Dan Magenheimer List-Id: xen-devel@lists.xenproject.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --===============2127628285== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig45D0EC965C0463A2B4EE03B4" This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig45D0EC965C0463A2B4EE03B4 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 03/12/2010 01:49 AM, Jeremy Fitzhardinge wrote: > On 03/11/2010 04:27 PM, Joanna Rutkowska wrote: >> I think that the important clue is this message appearing in my dmesg >> (in Dom0 and also in DomUs): >> >> hrtimer: interrupt too slow, forcing clock min delta to 540150561 ns >> >> This is almost 0.5s (!) and I think this might explain my kbd hiccup. = I >> wrote that I feel it every 10s or so, but when I was playing on my >> system without jiffies setting today, I saw this hiccup occurring much= >> more often; in fact it was more of a "slow keyboard/system" feeling th= an >> a hiccup". >> =20 >=20 > Yes, its definitely a good clue. It could point to a Xen scheduler > issue (I assume you don't have any other busy domains when this is goin= g > on), but that wouldn't explain why it works OK with jiffies. Perhaps > there's a problem with programming the timer so that sometimes it gets > missed and the system doesn't get a kick until some subsequent event > (whereas with clocksource=3Djiffies there'll always be a timer in the n= ext > 100ms). >=20 One detail: when I boot the system and there is only Dom0 running, everything seems ok. Only after I start at least one VM the problem becomes noticeable. But the other VM(s) is pretty much idle (as xentop shows). When I kill all the other VMs, so that Dom0 is alone again, the problem does *not* seem to go away, strangely... j. --------------enig45D0EC965C0463A2B4EE03B4 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/ iEYEARECAAYFAkuZjOkACgkQORdkotfEW84aEACdFz06BNgA115beBfXPnYeXBVw mIYAmgJ6LleM7n8PROkj6SMY26Ten4FY =/Vk5 -----END PGP SIGNATURE----- --------------enig45D0EC965C0463A2B4EE03B4-- --===============2127628285== 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 --===============2127628285==--