Date: Thu, 31 Mar 2011 19:06:44 -0400 From: Arnaud Lacombe <lacombar@gmail.com> To: Jack Vogel <jfvogel@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: <AANLkTikmjmBKf9XUuSrYQz4T7xsR5ynvxHm2cjEDtFE%2B@mail.gmail.com> In-Reply-To: <AANLkTi=OVSOitMvdjHexbv-fu0fA1WWOHo7gm-=MtPRf@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> <AANLkTi=OVSOitMvdjHexbv-fu0fA1WWOHo7gm-=MtPRf@mail.gmail.com>
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Hi, On Thu, Mar 31, 2011 at 6:28 PM, Jack Vogel <jfvogel@gmail.com> wrote: > 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.=A0 What doe= s > netstat -m show? > # netstat -m 3073/74927/78000 mbufs in use (current/cache/total) 3070/29698/32768/32768 mbuf clusters in use (current/cache/total/max) 0/383 mbuf+clusters out of packet secondary zone in use (current/cache) 0/12800/12800/12800 4k (page size) jumbo clusters in use (current/cache/total/max) 0/0/0/6400 9k jumbo clusters in use (current/cache/total/max) 0/0/0/3200 16k jumbo clusters in use (current/cache/total/max) 6908K/129327K/136236K bytes allocated to network (current/cache/total) 0/1080/0 requests for mbufs denied (mbufs/clusters/mbuf+clusters) 0/0/0 requests for jumbo clusters denied (4k/9k/16k) 0/7/6656 sfbufs in use (current/peak/max) 0 requests for sfbufs denied 0 requests for sfbufs delayed 0 requests for I/O initiated by sendfile 0 calls to protocol drain routines Note that the mbuf allocation denial did not appended at once. It has been progressively increasing by block of ~200 over the 5h of uptime of the machine, until the current condition occurred. I have previously been trying to simulate the depletion and the hang, but the driver recovered. I assume the condition is met in em_local_timer() to refresh the ring, I'd still need to check that. - Arnaud > Jack > > > On Thu, Mar 31, 2011 at 3:15 PM, Arnaud Lacombe <lacombar@gmail.com> wrot= e: >> >> 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 ? >> >> =A0- 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 = in >> > 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 fo= r >> > 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 wh= y >> > 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_refill' >> >> > and the associated sysctl, re-run the tests and come back with >> >> > correct >> >> > 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 >> >> =A0-> -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 >> >> >> has >> >> >> exactly the >> >> >> same effect as checking for some interrupt cause, a cause that is >> >> >> not >> >> >> available >> >> >> when using MSIX on 82574, but this approach works for everything. >> >> >> >> >> Can you please point me to a reference datasheet (or errata), provide= d >> >> 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 = and >> >> 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 fo= ur >> >> vectors for >> >> queues and one vector for other causes). The requested number of >> >> vectors >> >> 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, >> >> =A0- Arnaud >> >> >> >> [0]: ftp://download.intel.com/design/network/datashts/82574.pdf >> > >> > > >
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