On Wed, Jan 21, 2015 at 09:32:11AM +0100, Hans Petter Selasky wrote: > On 01/21/15 00:53, Sean Bruno wrote: > > Unkown to me. Nor am I aware of anyone else who ever hit our panics > > either. Our environment, and the failure, was only seen in the Intel > > 10GE space (ixgbe). This is an artifact of our use cases, and hasn't > > been expanded nor tested in our environment with other vendor interfaces. > > > > sean > > Hi, > > I've seen this with Mellanox hardware when running some special tests, > but not during regular use yet. That was the reason for going into the > callout subsystem in the first place. 40GE. > > Also I would like to mention during the heat of this discussion, that > during X-mas this year, I had a very heavy discussion with Attilio and a > few other FreeBSD developers, who's name was on a patch (r220456) that > changed how the return value of "callout_active()" works. > "callout_active()" is heavily used inside the TCP stack and what was > found is there is a potential race related to migrating the callout from > one CPU to the other, which in turn might give other symptoms than a > spinlock hang. > > FYI: > > https://svnweb.freebsd.org/base?view=revision&revision=225057 > > Cite: "If the newly scheduled thread wants to acquire the old queue it > will just spin forever." > > This description reminds me very much of what "Jason Wolfe", others and > myself have seen. > > Konstantin, you're responsible for r220456 (Approved by: kib). I would I definitely do not see anything related to my freefall login in the log message for r220456, nor I participated in any way in the work which lead to that revision.
If you mean r225057, note that approval by re != review. > like to ask what investigation you did to ensure that you solved the > problem as described in the commit message and didn't introduce a new one? > > In r220456 the "callout_reset_on()" function was changed in a way that > directly conflicts with how the TCP stack works, by not always ensuring > that "callout_active()" returns non-zero after a callout is restarted! > See return at line 821: > > > https://svnweb.freebsd.org/base/head/sys/kern/kern_timeout.c?revision=225057&view=markup&pathrev=225057#l821 > > Kib: Any comments? With the re hat on, explanation for the proposed commit looked reasonable, and committer provided enough evidence that change got adequate testing. Since change fixed a bug, and this is exactly what re wants to see during release cycle, I see no reason why commit should be denied. _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
