Date: Mon, 29 Mar 2010 21:21:42 +0200 From: Attila Nagy <bra@fsn.hu> To: pyunyh@gmail.com Cc: Mailing List FreeBSD Stable <freebsd-stable@freebsd.org>, Michael Loftis <mloftis@wgops.com> Subject: Re: 8-STABLE freezes on UDP traffic (DNS), 7.x doesn't Message-ID: <4BB0FDC6.7050105@fsn.hu> In-Reply-To: <20100329183848.GE1473@michelle.cdnetworks.com> References: <4BAB718C.3090001@fsn.hu> <886B21E1787F0003B89E34B6@[192.168.1.44]> <4BB087B7.3030602@fsn.hu> <20100329183848.GE1473@michelle.cdnetworks.com>
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Pyun YongHyeon wrote: > On Mon, Mar 29, 2010 at 12:57:59PM +0200, Attila Nagy wrote: > >> Hi, >> >> Michael Loftis wrote: >> >>> --On Thursday, March 25, 2010 3:22 PM +0100 Attila Nagy <bra@fsn.hu> >>> wrote: >>> >>> <...> >>> >>>> Both unbound and python accepts DNS requests, and it seems when 25% >>>> interrupt happens, only unbound is in *udp state, where it is 50%, both >>>> programs are in that state. >>>> >>> Try turning of hardware TSO/checksum offload if it's availble on your >>> chipset? ifconfig <interface> -rxcsum -txcsum -tso -- I'm only using >>> nfe chips right now, but w/ the TSO/CSUM on they lock up constantly >>> under high load. We're pretty sure it's mostly the nfe driver, or the >>> chips themselves, but have never ruled out some generic 8.x hardware >>> offload issues. >>> >> Bingo, this solved the problem. The current uptime nears four days. >> Previously I couldn't go further than a day. >> >> The machine gets very light TCP load (and other machines which get work >> well), so I guess it's UDP RX or TX checksum related. >> >> > > Hmm, this is unexpected result. Since you're using UDP, TSO is not > involved in this issue. Because you disabled RX/TX checksum > offloading could you check how many number of 'bad checksum' and > and 'no checksum' you have from netstat(1)? > To narrow down which side of checksum offloading causes the issue, > would you just disable one side in a time? For instance, disable TX > checksum offloading with RX checksum offloading enabled and see how > bce(4) works. > #ifconfig bce0 -txcsum rxcsum > If that shows the same issue, try disabling RX checksum offloading > but enabling TX checksum offloading. > #ifconfig bce0 txcsum -rxcsum > It's interesting. During the day, I've disabled only HW checksumming and left TSO enabled. It couldn't run more than a few hours. I have disabled tso again to see what happens. BTW, of course there is TCP traffic on that interface (DNS is also available on TCP), maybe this causes the problem.
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