Date: Thu, 31 Mar 2011 15:28:46 -0700 From: Jack Vogel <jfvogel@gmail.com> To: Arnaud Lacombe <lacombar@gmail.com> Cc: freebsd-net@freebsd.org Subject: Re: em(4) hang [Was: Re: igb(4) won't start with "igb0: Could not setup receive structures"] Message-ID: <AANLkTi=OVSOitMvdjHexbv-fu0fA1WWOHo7gm-=MtPRf@mail.gmail.com> In-Reply-To: <AANLkTina-MO4GuK66ZJN0hipp%2BVCa-CUxEz79rzRt-cZ@mail.gmail.com> References: <AANLkTin64gGxRituE2B%2BsfVpRXt2QetdNLaV7HCf0uNE@mail.gmail.com> <AANLkTi=OjzMrjCPZ2VFDBf6URTaMoAzQqXbxWLv3d9mW@mail.gmail.com> <AANLkTikvbvr%2BY=Fh2fPVieHkTRix%2Bni61jVPct10NKfD@mail.gmail.com> <AANLkTina-MO4GuK66ZJN0hipp%2BVCa-CUxEz79rzRt-cZ@mail.gmail.com>
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OK, but those are not something present in this data, that was what I'm asking. So, you have a hang for which we do not have a certain cause. What does netstat -m show? Jack On Thu, Mar 31, 2011 at 3:15 PM, Arnaud Lacombe <lacombar@gmail.com> wrote: > Hi, > > On Thu, Mar 31, 2011 at 5:57 PM, Jack Vogel <jfvogel@gmail.com> wrote: > > So, what is the evidence that the driver is stuck here? > > > About 800 pps (mostly SYN) present wire but never ever seen on em0, > plus a couple of ARP reply, which still never hit em0, plus the > `missed_packets' count increasing by the same 800 pps in the last > hour. Is that enough ? > > - Arnaud > > ps: I forgot to add that MAC address on the wire are fine. > > > I see that next_to_check !=3D next_to_refresh, which is why the > > local timer won't schedule anything. OH, and I also realized there > > is a problem with local_timer anyway, it will run rxeof, but that won't > help > > if you can't enter the loop, so I need to add some code at the top to > > call em_refresh_mbufs() when in this state. > > > > On this interrupt cause that you are focused upon, although its there i= n > the > > design, I had talked with some of our most seasoned developers on both > > the Windows and Linux side of the house, and NO one has ever used this > > 'feature', because (and I'm quoting here) "there's no good use case for > it". > > Meaning, there's always some simpler way of handling the issue. > > > > When you use MSIX you can't read causes btw, if you configured it, it > would > > mean you'd just get into the regular RX handler, same as always, so why > > some special bother with this cause? > > > > On non-MSIX hardware there is just no particular reason to worry about > the > > cause either, we can just handle the RX situation in the interrupt > handler. > > > > Jack > > > > > > On Thu, Mar 31, 2011 at 2:09 PM, Arnaud Lacombe <lacombar@gmail.com> > wrote: > >> > >> Hi Jack, > >> > >> On Thu, Mar 31, 2011 at 9:51 AM, Arnaud Lacombe <lacombar@gmail.com> > >> wrote: > >> > [...] > >> > I'll remove part of the changes I made to keep only `rx_forced_refil= l' > >> > and the associated sysctl, re-run the tests and come back with corre= ct > >> > value, hopefully in a few hours. > >> > > >> Here it is: > >> > >> # sysctl dev.em.0.%desc > >> dev.em.0.%desc: Intel(R) PRO/1000 Network Connection 7.2.2 > >> > >> # sysctl dev.em.0.mac_stats.missed_packets > >> dev.em.0.mac_stats.missed_packets: 917428 > >> > >> # sysctl dev.em.0.debug=3D1 > >> dev.em.0.debug: I-1nterface is RUNNING and INACTIVE > >> em0: hw tdh =3D 975, hw tdt =3D 975 > >> em0: hw rdh =3D 884, hw rdt =3D 885 > >> em0: Tx Queue Status =3D 0 > >> em0: TX descriptors avail =3D 1024 > >> em0: Tx Descriptors avail failure =3D 0 > >> em0: RX discarded packets =3D 0 > >> em0: RX Next to Check =3D 884 > >> em0: RX Next to Refresh =3D 885 > >> -> -1 > >> > >> So the taskqueue cannot be scheduled to run and the driver is stuck. > >> > >> > On Wed, Mar 30, 2011 at 2:22 PM, Jack Vogel <jfvogel@gmail.com> > wrote: > >> >> Read the code in HEAD, em_local_timer() has a test of ALL the rx > queues > >> >> and > >> >> will schedule a task that refreshes mbufs if they are empty. This h= as > >> >> exactly the > >> >> same effect as checking for some interrupt cause, a cause that is n= ot > >> >> available > >> >> when using MSIX on 82574, but this approach works for everything. > >> >> > >> Can you please point me to a reference datasheet (or errata), provided > >> by Intel, about the RX Overrun interrupt not being available with > >> MSI-X on the 82574 ? > >> > >> Currently, I only have access to [0], which precises the following: > >> > >> 7.4 Interrupts > >> 7.4.2 MSI-X Mode > >> [...] > >> The following configuration and parameters are involved: > >> =95 The IVAR.INT_Alloc[4:0] entries map two Tx queues, two Rx queues a= nd > >> other > >> events to 5 interrupt vectors > >> =95 The ICR[24:20] bits reflect specific interrupt causes > >> =95 Five MSI-X interrupt vectors are provided (calculated based on fou= r > >> vectors for > >> queues and one vector for other causes). The requested number of vecto= rs > >> is > >> loaded from the MSI_X_N fields in the EEPROM into the PCIe MSI-X > >> capability > >> structure of the function. > >> > >> 10.2.4.1 Interrupt Cause Read Register - ICR (0x000C0; RC/WC) > >> [...] > >> > >> about bit 24: > >> > >> Other Interrupt. Indicates one of the following interrupts was set: > >> =95 Link Status Change. > >> =95 Receiver Overrun. > >> =95 MDIO Access Complete. > >> =95 Small Receive Packet Detected. > >> =95 Receive ACK Frame Detected. > >> =95 Manageability Event Detected. > >> > >> Thanks in advance, > >> - Arnaud > >> > >> [0]: ftp://download.intel.com/design/network/datashts/82574.pdf > > > > >
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