Date: Wed, 9 Jan 2008 16:30:03 GMT From: "Remko Lodder" <remko@elvandar.org> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/119487: page fault in em taskq with polling enabled Message-ID: <200801091630.m09GU3Eh090551@freefall.freebsd.org>
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The following reply was made to PR kern/119487; it has been noted by GNATS. From: "Remko Lodder" <remko@elvandar.org> To: =?iso-8859-1?Q?=C5ke_Wallebom?= <ake@ake.nu> Cc: freebsd-gnats-submit@freebsd.org Subject: Re: kern/119487: page fault in em taskq with polling enabled Date: Wed, 9 Jan 2008 17:29:30 +0100 (CET) > FreeBSD dunder 7.0-RC1 FreeBSD 7.0-RC1 #2: Tue Jan 8 22:29:24 CET 2008 > removed@dunder:/usr/obj/usr/src/sys/CUSTOM amd64 > >>Description: > I got a page fault with 'current process' being 'em0 taskq' while > transferring about 200 GB of data from an ftp server to my FreeBSD box via > Gigabit LAN. > > I had compiled my kernel with DEVICE_POLLING and HZ=2000, and > kern.polling.enable was set to 1 (I noticed later that this was > deprecated). > > The files were transfered onto a ZFS pool on a GELI-device (1TB > SATA2-drive). > > After transferring 150 GB i got the above error and the kernel panic'ed. > > Sadly, I can't remember the whole error message. > > More about the machine: > > Core 2 Duo E6750 > 4 GB RAM > Three Intel PRO/1000 GT Desktop NICs (Single port cards) >>How-To-Repeat: > I really don't know... > > Hasn't happened again - but I have now recompiled the kernel with just > 'POLLING' set, using default HZ now. And now i don't enable polling via > sysctl but via ifconfig xxx polling. > > Transfered 180 GB and did not crash. So I guess I'm just reporting this as > a curiosity for the em driver developer(s). >>Fix: > Decrease the HZ value? > Set polling via ifconfig instead of kern.polling.enable? > One of the things: dont use polling with em cards, it's not needed and could have negative impact on your machine. Also, if you get a crash, please try to obtain a kernel crashdump so that we can see what is going on and understand it and fix it ;-) You can see more details about that on http://www.freebsd.org/doc/en/books/developers-handbook/kerneldebug.html Without it, it's just looking in the blind. In addition; can you test this without polling enabled at all? Cheers, Remko -- /"\ Best regards, | remko@FreeBSD.org \ / Remko Lodder | remko@EFnet X http://www.evilcoder.org/ | / \ ASCII Ribbon Campaign | Against HTML Mail and News
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