Date: Tue, 19 Oct 2004 18:08:06 -0400 (EDT) From: Andrew Gallatin <gallatin@cs.duke.edu> To: Robert Watson <rwatson@freebsd.org> Cc: freebsd-current@freebsd.org Subject: Re: mbuf leak with SMP and debug.mpsafenet=1 Message-ID: <16757.36934.576905.271257@grasshopper.cs.duke.edu> In-Reply-To: <Pine.NEB.3.96L.1041019174802.81058C-100000@fledge.watson.org> References: <16757.34627.710821.812489@grasshopper.cs.duke.edu> <Pine.NEB.3.96L.1041019174802.81058C-100000@fledge.watson.org>
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Robert Watson writes: > > On Tue, 19 Oct 2004, Andrew Gallatin wrote: > > > I hooked up the em0 GbE interfaces, and that leaks nearly as bad as my > > myrinet nic (at least with a linux sender, hooked back-to-back). Em0 > > seems to be leaking at a few thoundsand pkts/sec, so I wasn't brave > > enough to do a long run.. > > Oh, I just had a thought. Could you try this patch (perhaps with tweaks > to apply to recent kernels): > > http://www.watson.org/~robert/freebsd/netperf/20040910-atomic-mballoc.diff > > I ran with this change in the netperf branch for quite a long time, but > never managed to trigger sufficient races on the allocator to result in > the counters getting off by more than a couple. However, the reason I > updated the patch and put it on the netperf page was that Bill Paul > reported seeing fairly hefty stats errors on an SMP box at gig-e rates, > and when he tried the patch it went away. It would be useful if you could > try the patch to make sure that we're looking at a real mbuf leak and not > an mbuf stat leak. Aha! That seems to be it (a stats leak). This is kind of a shame, since the last thing a P4 needs is more atomic ops :-( I think there may have been a real leak in the past; at least I ran a box out of mbufs a week ago. It only came back when I ifconfig'ed down my driver, freeing a bunch of mbufs. But this was before green's recent mbuf leak fix, and in the middle of driver development. So who knows.. Drew
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