Date: Wed, 14 Nov 2007 01:49:36 +0100 From: Kris Kennaway <kris@FreeBSD.org> To: Kip Macy <kip.macy@gmail.com> Cc: Vivek Khera <vivek@khera.org>, FreeBSD Stable List <freebsd-stable@freebsd.org> Subject: Re: reboot after panic: vm_page_unwire: invalid wire count: 0 Message-ID: <473A4620.8010909@FreeBSD.org> In-Reply-To: <b1fa29170711131413g70af61bch1fb29ea917068272@mail.gmail.com> References: <0ECA0F43-497A-4823-8731-D517889D5822@khera.org> <ad79ad6b0711131350u7c00fb0ek16a23f5dc12089cb@mail.gmail.com> <91893E44-B766-4B31-9DA7-62F5EC0CCD45@khera.org> <b1fa29170711131413g70af61bch1fb29ea917068272@mail.gmail.com>
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Kip Macy wrote: > Unfortunately, ZERO_COPY_SOCKETs have long been a known source of > problems. I think also, when a page is copied as part of COW the new > page is unwired (see pmap_copy et al.), this could lead to > socow_iodone unwiring after send a page that was not wired. An added > issue is that parts of the VM assume that COW and wired are mutually > exclusive which the socow code violates. > > At some point in the near future I may be adding support for doing > zero copy send without COW for blocking sockets. The one down side of > this approach is that if you have multiple threads in your process it > widens the window during which they can stomp on data that you're > sending. Nonetheless, this would be a bug in the application code. > More complicated would be zero-copy non-COW send on non-blocking > sockets as it would require an extension to kevent for completion > notification. > > In the meantime, your best bet is to disable ZERO_COPY_SOCKETS. There is a chance this was a recent regression, previously in 7.0 they were believed to work. Kris > > > -Kip > > > > On Nov 13, 2007 1:59 PM, Vivek Khera <vivek@khera.org> wrote: >> On Nov 13, 2007, at 4:50 PM, Vlad GALU wrote: >> >>>> vmio = 1 >>>> offset = Unhandled dwarf expression opcode 0x93 >>>> (kgdb) >>>> >>> Do you happen to have ZERO_COPY_SOCKETS in your kernel config? >>> >>> >> Yes, I do. Are they known to be bad under certain loads or just in >> general. I don't have this issue with any other web server running >> the same kernel config but those are amd64 boxes mostly. >> >> >> _______________________________________________ >> freebsd-stable@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-stable >> To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org" >> > _______________________________________________ > freebsd-stable@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-stable > To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org" > >
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