Date: Thu, 10 Sep 2009 11:46:45 -0700 From: Julian Elischer <julian@elischer.org> To: Linda Messerschmidt <linda.messerschmidt@gmail.com> Cc: freebsd-hackers@freebsd.org Subject: Re: Intermittent system hangs on 7.2-RELEASE-p1 Message-ID: <4AA94995.6030700@elischer.org> In-Reply-To: <237c27100909101129y28771061o86db3c6a50a640eb@mail.gmail.com> References: <237c27100908261203g7e771400o2d9603220d1f1e0b@mail.gmail.com> <200908261642.59419.jhb@freebsd.org> <237c27100908271237y66219ef4o4b1b8a6e13ab2f6c@mail.gmail.com> <200908271729.55213.jhb@freebsd.org> <237c27100909100946q3d186af3h66757e0efff307a5@mail.gmail.com> <bc2d970909100957y6d7fd707g9f3184165f8cb766@mail.gmail.com> <237c27100909101129y28771061o86db3c6a50a640eb@mail.gmail.com>
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Linda Messerschmidt wrote: > On Thu, Sep 10, 2009 at 12:57 PM, Ryan Stone<rysto32@gmail.com> wrote: >> You should be able to run schedgraph.py on a windows machine with python >> installed. It works just fine for me on XP. > > Don't have any of those either, but I *did* get it working on a Mac > right out of the box. Should have thought of that sooner. :) > > The output looks pretty straightforward, but there are a couple of > things I find odd. > > First, there's a point right around what I estimate to be the problem > time where schedgraph.py indicates gmond (the Ganglia monitor) was > running uninterrupted for a period of exactly 1 second. However, it > also indicates that both CPU's idle tasks were *also* running almost > continuously during that time (subject to clock/net interrupts), and > that the run queue on both CPU's was zero for most of that second > while gmond was allegedly running. I've noticed that schedgraph tends to show the idle threads slightly skewed one way or the other. I think there is a cumulative rounding error in the way they are drawn due to the fact that they are run so often. Check the raw data and I think you will find that you just need to imagine the idle threads slightly to the left or right a bit. The longer the trace and the further to he right you are looking the more "out" the idle threads appear to be. I saw this on both Linux and Mac python implementations. > > Second, the interval I graphed was about nine seconds. During that > time, the PHP command line script made a whole lot of requests: it > usleeps 50ms between requests, and non-broken requests average about > 1.4ms. So even with the stalled request chopping 2 seconds off the > end, there should be somewhere in the neighborhood of 130 requests > during the graphed period. But that php process doesn't appear in the > schedgraph output at all. > > So that doesn't make a whole lot of sense to me. > > I'll try to get another trace and see if that happens the same way again. > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org"
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