Date: Mon, 17 Jul 2006 15:33:35 +0100 From: Gareth McCaughan <gmccaughan@synaptics-uk.com> To: Alex Zbyslaw <xfb52@dial.pipex.com> Cc: freebsd-questions <freebsd-questions@freebsd.org> Subject: Re: "swiN: clock sio" process taking 75% CPU Message-ID: <200607171533.35657.gmccaughan@synaptics-uk.com> In-Reply-To: <44BB980C.1040807@dial.pipex.com> References: <200607132002.43637.gmccaughan@synaptics-uk.com> <200607171430.27752.gmccaughan@synaptics-uk.com> <44BB980C.1040807@dial.pipex.com>
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> Can I suggest that if you get no replies on questions@ that you try > hackers@ (you may need to subscribe to post, not sure). > > What's going on here is not normal so even someone with tons of FreeBSD > experience may never have seen something like this. I know I never > have. Most posters here are not kernel hackers. That's a fair comment. I tried -stable too; I'm fairly sure some people there *are* kernel hackers; but -hackers is probably not a bad place to look for deeper wizardry. > > It would be a shame if the only conclusion to be drawn from this were > > "sometimes a machine running FreeBSD is just 4x slower than it should > > be, and no one knows why". > > Well, if you could only find one somewhat relevant topic with google, > then "sometimes" would be "almost never". I appreciate that you are > frustrated because it *is* happening to you, but your problem is not a > common one so may take more than a post on questions to resolve. I found quite a lot of relevant messages. In every case what happened was that someone posted saying "I've got this weird thing where X% of my CPU time is being taken up by this clock sio thing" and they got no responses other than from other people saying "yup, that's strange". (Sometimes there was something else they were also concerned about, and they got responses to that bit.) A few examples found by googling for "clock sio site:lists.freebsd.org" follow; most appear to have been asked only on -stable, and it was because this seems to have been an unsuccessful strategy that I tried -questions too. :-) http://lists.freebsd.org/pipermail/freebsd-stable/2006-April/024793.html (16%; old system with modems attached, which were also giving problems; the latter was resolved, kinda, but it's not clear that the former was) http://lists.freebsd.org/pipermail/freebsd-stable/2006-July/026873.html (not clear how much CPU; his concern was something else that was triggered by this, and he had another kernel thread being silly too; no resolution) http://lists.freebsd.org/pipermail/freebsd-stable/2004-December/010673.html (not certain that this is the same problem, but it sure looks like it; no reply to his message) http://lists.freebsd.org/pipermail/freebsd-stable/2004-November/009489.html (24% on one machine, 8% on another; no reply) http://lists.freebsd.org/pipermail/freebsd-current/2005-March/047218.html (18% but drops when a real task begins; may not be the same problem; this is under MS Virtual Server; only suggestion was to reduce HZ, which didn't solve the problem; no further replies) However, I've not seen any sign that other people have had *as much* CPU wasted this way as I have. -- g
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