Date: Thu, 15 Mar 2012 12:45:39 -0400 From: Arnaud Lacombe <lacombar@gmail.com> To: Jack Vogel <jfvogel@gmail.com> Cc: Juli Mallett <jmallett@freebsd.org>, freebsd-net@freebsd.org Subject: Re: MSI-X + em(4) = Refresh mbufs: hdr dmamap load failure - 22 Message-ID: <CACqU3MXw77yc0=SHoUVora11OLDkVL1A2i91whHYKkaWSNJB4Q@mail.gmail.com> In-Reply-To: <CAFOYbc=sYofj=phGu5M%2BSDSyorq5VPFKsVUpBVYquFtrfALAyQ@mail.gmail.com> References: <CACVs6=9rTNAjEEdy7sBNEWPtoTdkx7eifZisQF5JTESAorQeJQ@mail.gmail.com> <CAFOYbc=sYofj=phGu5M%2BSDSyorq5VPFKsVUpBVYquFtrfALAyQ@mail.gmail.com>
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Hi, On Thu, Mar 15, 2012 at 12:07 PM, Jack Vogel <jfvogel@gmail.com> wrote: > You have header split on?? I've not seen this before so something odd > is going on. > AFAIK, you never implemented header-split on em(4), despite hardware supporting it, so that question is pointless. - Arnaud > Jack > > > On Thu, Mar 15, 2012 at 12:39 AM, Juli Mallett <jmallett@freebsd.org> wro= te: > >> All, >> >> On both stable/9 and trunk I see that with one of either the 82571EB >> or 82574L I am flooded with messages in the form of: >> >> Refresh mbufs: hdr dmamap load failure - 22 >> >> If I disable msix, then the messages go away. =A0I am not sure why msix >> vs. non-msix would matter in this case unless in the msix case there's >> some kind of case of spurious interrupts causing em_rxeof to be called >> without any packets available. =A0If that happens then perhaps >> e1000_rx_unrefreshed() is called when no buffers have been processed >> and then em_refresh_mbufs wrongly refreshes the whole ring? >> >> This seems like it would be a problem because the >> bus_dmamap_load_mbuf_sg code is called unconditionally, even when a >> new mbuf isn't being allocated. =A0In that case, the mapping already >> exists. =A0Wouldn't it be necessary to unload and then reload the mbuf? >> So either it's a bug that em_refresh_mbufs is being called at all, or >> it's naively reusing mbufs in a way that actually guarantees an error, >> right? =A0Also, in the case where it frees, only m_free is called =97 is >> there never a case where that should be an m_freem? =A0I can imagine >> some, but they are likely impossible with the receive path of the >> driver. =A0(I don't know for sure because the receive path and the mbuf >> refresh code keep changing and I've been unable to keep up.) >> >> I don't know which part it is, of course, because I don't know what >> port it's coming from. =A0Like three other printfs in the driver where >> which device is being used matters tremendously, it uses a bare printf >> and not a device_printf. =A0I could modify the driver, but for now >> disabling msix is easier than continuing to load new kernels to try to >> debug the problem. >> >> Is anyone else seeing this? =A0Has anyone further investigated the >> problem? =A0Is there a patch floating around and I just haven't found >> the right search terms? >> >> Thanks in advance, >> Juli. >> >> PS: Yes, I know this is kind of a crappy bug report, sorry. =A0I've had >> a limited amount of time to investigate so far, and don't want to >> delay reporting it until I am able to get more time with the >> problematic hardware. >> _______________________________________________ >> freebsd-net@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-net >> To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" >> > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
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