Date: Wed, 14 Jul 2004 20:33:55 -0400 (EDT) From: Andrew Gallatin <gallatin@cs.duke.edu> To: Doug White <dwhite@gumbysoft.com> Cc: Gary Stanley <gary@outloud.org> Subject: Re: Network related procs hang in unusual sfpbsy state Message-ID: <16629.53491.242495.5678@grasshopper.cs.duke.edu> In-Reply-To: <20040713184408.W527@carver.gumbysoft.com> References: <6.1.2.0.2.20040712142407.02d38a98@64.124.166.215> <20040713184408.W527@carver.gumbysoft.com>
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Doug White writes: > On Mon, 12 Jul 2004, Gary Stanley wrote: > > > New current kernel from about 3 days ago, certain processes hang after > > about a day in this state; > > > > 80 599 1 0 -16 -2 59020 53548 sfpbsy D< ?? 1141:08.65 > > /mnt/zeus/web/bin/zeus.web > > sfpbsy is used in do_sendfile(). It blocks on this if a page for the file > its trying to send is busy. It may be blocked on another process or the > volume its on is taking a while to page the page in. You might check the > logs or whatever for zeus and see if all of them are hung trying to > request the same file, or if its on the same filesystem. > > Anyone who understands the reason things get marked PG_BUSY can chime in > here :) It basically means "don't touch this page" and is set when the page is being changed. Eg, when vm_fault() is working with a page, or when vm_page_alloc() is allocating one. Sendfile sleeps with also_m_busy=TRUE, which means that it could be waiting for an io to complete and cause m->busy to drop to zero. (vm_page_io_finish()). Drew
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