Date: Wed, 23 Aug 2006 19:51:18 +0900 From: Pyun YongHyeon <pyunyh@gmail.com> To: Gleb Smirnoff <glebius@FreeBSD.org> Cc: freebsd-current@FreeBSD.org Subject: Re: call for bge(4) testers Message-ID: <20060823105118.GJ17902@cdnetworks.co.kr> In-Reply-To: <20060823100420.GG96644@cell.sick.ru> References: <20060822042023.GC12848@cdnetworks.co.kr> <20060823093741.GF96644@FreeBSD.org> <20060823095504.GI17902@cdnetworks.co.kr> <20060823100420.GG96644@cell.sick.ru>
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On Wed, Aug 23, 2006 at 02:04:20PM +0400, Gleb Smirnoff wrote: > On Wed, Aug 23, 2006 at 06:55:04PM +0900, Pyun YongHyeon wrote: > P> On Wed, Aug 23, 2006 at 01:37:41PM +0400, Gleb Smirnoff wrote: > P> > On Tue, Aug 22, 2006 at 01:20:23PM +0900, Pyun YongHyeon wrote: > P> > P> After fixing em(4) watchdog bug, I looked over bge(4) and I think > P> > P> bge(4) may suffer from the same issue. So if you have seen occasional > P> > P> watchdog timeout errors on bge(4) please give the attached patch a try. > P> > P> The patch does fix false watchdog timeout error only. > P> > P> Typical pheonoma for false watchdog timeout error are > P> > P> o polling(4) fix the issue > P> > P> o random watchdog error > P> > P> > P> > P> If my patch fix the issue you could see the following messages. > P> > P> "missing Tx completion interrupt!" or "link lost -- resetting" > P> > > P> > I still think that this fix is incorrect. It is just a more gentle > P> > recovery from a fake watchdog timeout. > P> > P> Its sole purpose is to reinitialize hardware for real watchdog > P> timeouts. It's not fix for general watchdog timeouts. As I said other > P> mails, the fake watchdog timeout(losing Tx interrupts) for hardwares > P> with Tx interrupt moderation capability could be normal thing. So I > P> just want to know bge(4) also has the same feature(bug). > > According to several emails about em(4) fake watchdog timeouts, the > problem can be fixed by setting debug.mpsafenet=0. This makes me think > that the problem isn't caused by TX interrupt moderation, but some race > in the kernel. Really, if_slowtimo() doesn't acquire driver lock before > checking and modifying the if_timer field. > Hmm... I didn't say the problem was caused by TX interrupt moderation. I can't sure but I'm under the impression it has *two* different issues. If you think fake watchdog timeout fix is not adequate one please let me know. I'll backout the change if you want. > Afaik, NIC drivers that can do interrupt moderation should set a timer > to a sane value, based on interrupt moderation settings, so that the > watchdog won't be ever called fakely. > Yes. Normally it should. But I saw the issues on Marvell Yukon too. > P> > The more I think, the more I doubt that we really need the > P> > watchdog infrastructure that comes from old days. > P> > P> Would you give other way to recover from Tx stuck condition without > P> using watchdog? > > May be driver should take care of that theirselves, why not? At least > the callout routine will have access to the driver mutex, contrary to > if_slowtimo(). > -- Regards, Pyun YongHyeon
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