9.2 ixgbe tx queue hang
Christopher Forgeron
csforgeron at gmail.com
Sat Mar 22 03:14:10 UTC 2014
Ah yes, I see it now: Line #658
#if defined(INET) || defined(INET6)
/* Initialize to max value. */
if (ifp->if_hw_tsomax == 0)
ifp->if_hw_tsomax = IP_MAXPACKET;
KASSERT(ifp->if_hw_tsomax <= IP_MAXPACKET &&
ifp->if_hw_tsomax >= IP_MAXPACKET / 8,
("%s: tsomax outside of range", __func__));
#endif
Should this be the location where it's being set rather than in ixgbe? I
would assume that other drivers could fall prey to this issue.
Also should we not also subtract ETHER_VLAN_ENCAP_LEN from tsomax to make
sure VLANs fit?
Perhaps there is something in the newer network code that is filling up the
frames to the point where they are full - thus a TSO = IP_MAXPACKET is just
now causing problems.
I'm back on the 9.2-STABLE ixgbe with the tso patch for now. I'll make it
run overnight while copying a few TB of data to make sure it's stable there
before investigating the 10.0-STABLE driver more.
..and there is still the case of the denied jumbo clusters on boot -
something else is off someplace.
BTW - In all of this, I did not mention that my ix0 uses a MTU of 9000 - I
assume others assumed this.
On Fri, Mar 21, 2014 at 11:39 PM, Rick Macklem <rmacklem at uoguelph.ca> wrote:
> Christopher Forgeron wrote:
> > It may be a little early, but I think that's it!
> >
> > It's been running without error for nearly an hour - It's very rare
> > it
> > would go this long under this much load.
> >
> > I'm going to let it run longer, then abort and install the kernel
> > with the
> > extra printfs so I can see what value ifp->if_hw_tsomax is before you
> > set
> > it.
> >
> I think you'll just find it set to 0. Code in if_attach_internal()
> { in sys/net/if.c } sets it to IP_MAXPACKET (which is 65535) if it
> is 0. In other words, if the if_attach routine in the driver doesn't
> set it, this code sets it to the maximum possible value.
>
> Here's the snippet:
> /* Initialize to max value. */
> 657 if (ifp->if_hw_tsomax == 0)
> 658 ifp->if_hw_tsomax = IP_MAXPACKET;
>
> Anyhow, this sounds like progress.
>
> As far as NFS is concerned, I'd rather set it to a smaller value
> (maybe 56K) so that m_defrag() doesn't need to be called, but I
> suspect others wouldn't like this.
>
> Hopefully Jack can decide if this patch is ok?
>
> Thanks yet again for doing this testing, rick
> ps: I've attached it again, so Jack (and anyone else who reads this)
> can look at it.
> pss: Please report if it keeps working for you.
>
> > It still had netstat -m denied entries on boot, but they are not
> > climbing
> > like they did before:
> >
> >
> > $ uptime
> > 9:32PM up 25 mins, 4 users, load averages: 2.43, 6.15, 4.65
> > $ netstat -m
> > 21556/7034/28590 mbufs in use (current/cache/total)
> > 4080/3076/7156/6127254 mbuf clusters in use (current/cache/total/max)
> > 4080/2281 mbuf+clusters out of packet secondary zone in use
> > (current/cache)
> > 0/53/53/3063627 4k (page size) jumbo clusters in use
> > (current/cache/total/max)
> > 16444/118/16562/907741 9k jumbo clusters in use
> > (current/cache/total/max)
> > 0/0/0/510604 16k jumbo clusters in use (current/cache/total/max)
> > 161545K/9184K/170729K bytes allocated to network
> > (current/cache/total)
> > 17972/2230/4111 requests for mbufs denied
> > (mbufs/clusters/mbuf+clusters)
> > 0/0/0 requests for mbufs delayed (mbufs/clusters/mbuf+clusters)
> > 0/0/0 requests for jumbo clusters delayed (4k/9k/16k)
> > 35/8909/0 requests for jumbo clusters denied (4k/9k/16k)
> > 0 requests for sfbufs denied
> > 0 requests for sfbufs delayed
> > 0 requests for I/O initiated by sendfile
> >
> > - Started off bad with the 9k denials, but it's not going up!
> >
> > uptime
> > 10:20PM up 1:13, 6 users, load averages: 2.10, 3.15, 3.67
> > root at SAN0:/usr/home/aatech # netstat -m
> > 21569/7141/28710 mbufs in use (current/cache/total)
> > 4080/3308/7388/6127254 mbuf clusters in use (current/cache/total/max)
> > 4080/2281 mbuf+clusters out of packet secondary zone in use
> > (current/cache)
> > 0/53/53/3063627 4k (page size) jumbo clusters in use
> > (current/cache/total/max)
> > 16447/121/16568/907741 9k jumbo clusters in use
> > (current/cache/total/max)
> > 0/0/0/510604 16k jumbo clusters in use (current/cache/total/max)
> > 161575K/9702K/171277K bytes allocated to network
> > (current/cache/total)
> > 17972/2261/4111 requests for mbufs denied
> > (mbufs/clusters/mbuf+clusters)
> > 0/0/0 requests for mbufs delayed (mbufs/clusters/mbuf+clusters)
> > 0/0/0 requests for jumbo clusters delayed (4k/9k/16k)
> > 35/8913/0 requests for jumbo clusters denied (4k/9k/16k)
> > 0 requests for sfbufs denied
> > 0 requests for sfbufs delayed
> > 0 requests for I/O initiated by sendfile
> >
> > This is the 9.2 ixgbe that I'm patching into 10.0, I'll move into the
> > base
> > 10.0 code tomorrow.
> >
> >
> > On Fri, Mar 21, 2014 at 8:44 PM, Rick Macklem <rmacklem at uoguelph.ca>
> > wrote:
> >
> > > Christopher Forgeron wrote:
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > Hello all,
> > > >
> > > > I ran Jack's ixgbe MJUM9BYTES removal patch, and let iometer
> > > > hammer
> > > > away at the NFS store overnight - But the problem is still there.
> > > >
> > > >
> > > > From what I read, I think the MJUM9BYTES removal is probably good
> > > > cleanup (as long as it doesn't trade performance on a lightly
> > > > memory
> > > > loaded system for performance on a heavily memory loaded system).
> > > > If
> > > > I can stabilize my system, I may attempt those benchmarks.
> > > >
> > > >
> > > > I think the fix will be obvious at boot for me - My 9.2 has a
> > > > 'clean'
> > > > netstat
> > > > - Until I can boot and see a 'netstat -m' that looks similar to
> > > > that,
> > > > I'm going to have this problem.
> > > >
> > > >
> > > > Markus: Do your systems show denied mbufs at boot like mine does?
> > > >
> > > >
> > > > Turning off TSO works for me, but at a performance hit.
> > > >
> > > > I'll compile Rick's patch (and extra debugging) this morning and
> > > > let
> > > > you know soon.
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > On Thu, Mar 20, 2014 at 11:47 PM, Christopher Forgeron <
> > > > csforgeron at gmail.com > wrote:
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > BTW - I think this will end up being a TSO issue, not the patch
> > > > that
> > > > Jack applied.
> > > >
> > > > When I boot Jack's patch (MJUM9BYTES removal) this is what
> > > > netstat -m
> > > > shows:
> > > >
> > > > 21489/2886/24375 mbufs in use (current/cache/total)
> > > > 4080/626/4706/6127254 mbuf clusters in use
> > > > (current/cache/total/max)
> > > > 4080/587 mbuf+clusters out of packet secondary zone in use
> > > > (current/cache)
> > > > 16384/50/16434/3063627 4k (page size) jumbo clusters in use
> > > > (current/cache/total/max)
> > > > 0/0/0/907741 9k jumbo clusters in use (current/cache/total/max)
> > > >
> > > > 0/0/0/510604 16k jumbo clusters in use (current/cache/total/max)
> > > > 79068K/2173K/81241K bytes allocated to network
> > > > (current/cache/total)
> > > > 18831/545/4542 requests for mbufs denied
> > > > (mbufs/clusters/mbuf+clusters)
> > > >
> > > > 0/0/0 requests for mbufs delayed (mbufs/clusters/mbuf+clusters)
> > > > 0/0/0 requests for jumbo clusters delayed (4k/9k/16k)
> > > > 15626/0/0 requests for jumbo clusters denied (4k/9k/16k)
> > > >
> > > > 0 requests for sfbufs denied
> > > > 0 requests for sfbufs delayed
> > > > 0 requests for I/O initiated by sendfile
> > > >
> > > > Here is an un-patched boot:
> > > >
> > > > 21550/7400/28950 mbufs in use (current/cache/total)
> > > > 4080/3760/7840/6127254 mbuf clusters in use
> > > > (current/cache/total/max)
> > > > 4080/2769 mbuf+clusters out of packet secondary zone in use
> > > > (current/cache)
> > > > 0/42/42/3063627 4k (page size) jumbo clusters in use
> > > > (current/cache/total/max)
> > > > 16439/129/16568/907741 9k jumbo clusters in use
> > > > (current/cache/total/max)
> > > >
> > > > 0/0/0/510604 16k jumbo clusters in use (current/cache/total/max)
> > > > 161498K/10699K/172197K bytes allocated to network
> > > > (current/cache/total)
> > > > 18345/155/4099 requests for mbufs denied
> > > > (mbufs/clusters/mbuf+clusters)
> > > >
> > > > 0/0/0 requests for mbufs delayed (mbufs/clusters/mbuf+clusters)
> > > > 0/0/0 requests for jumbo clusters delayed (4k/9k/16k)
> > > > 3/3723/0 requests for jumbo clusters denied (4k/9k/16k)
> > > >
> > > > 0 requests for sfbufs denied
> > > > 0 requests for sfbufs delayed
> > > > 0 requests for I/O initiated by sendfile
> > > >
> > > >
> > > >
> > > > See how removing the MJUM9BYTES is just pushing the problem from
> > > > the
> > > > 9k jumbo cluster into the 4k jumbo cluster?
> > > >
> > > > Compare this to my FreeBSD 9.2 STABLE machine from ~ Dec 2013 :
> > > > Exact
> > > > same hardware, revisions, zpool size, etc. Just it's running an
> > > > older FreeBSD.
> > > >
> > > > # uname -a
> > > > FreeBSD SAN1.XXXXX 9.2-STABLE FreeBSD 9.2-STABLE #0: Wed Dec 25
> > > > 15:12:14 AST 2013 aatech at FreeBSD-Update
> > > > Server:/usr/obj/usr/src/sys/GENERIC amd64
> > > >
> > > > root at SAN1:/san1 # uptime
> > > > 7:44AM up 58 days, 38 mins, 4 users, load averages: 0.42, 0.80,
> > > > 0.91
> > > >
> > > > root at SAN1:/san1 # netstat -m
> > > > 37930/15755/53685 mbufs in use (current/cache/total)
> > > > 4080/10996/15076/524288 mbuf clusters in use
> > > > (current/cache/total/max)
> > > > 4080/5775 mbuf+clusters out of packet secondary zone in use
> > > > (current/cache)
> > > > 0/692/692/262144 4k (page size) jumbo clusters in use
> > > > (current/cache/total/max)
> > > > 32773/4257/37030/96000 9k jumbo clusters in use
> > > > (current/cache/total/max)
> > > >
> > > > 0/0/0/508538 16k jumbo clusters in use (current/cache/total/max)
> > > > 312599K/67011K/379611K bytes allocated to network
> > > > (current/cache/total)
> > > >
> > > > 0/0/0 requests for mbufs denied (mbufs/clusters/mbuf+clusters)
> > > > 0/0/0 requests for mbufs delayed (mbufs/clusters/mbuf+clusters)
> > > > 0/0/0 requests for jumbo clusters delayed (4k/9k/16k)
> > > > 0/0/0 requests for jumbo clusters denied (4k/9k/16k)
> > > > 0/0/0 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
> > > >
> > > > Lastly, please note this link:
> > > >
> > > >
> http://lists.freebsd.org/pipermail/freebsd-net/2012-October/033660.html
> > > >
> > > Hmm, this mentioned the ethernet header being in the TSO segment. I
> > > think
> > > I already mentioned my TCP/IP is rusty and I know diddly about TSO.
> > > However, at a glance it does appear the driver uses ether_output()
> > > for
> > > TSO segments and, as such, I think an ethernet header is prepended
> > > to the
> > > TSO segment. (This makes sense, since how else would the hardware
> > > know
> > > what ethernet header to use for the TCP segments generated.)
> > >
> > > I think prepending the ethernet header could push the total length
> > > over 64K, given a default if_hw_tsomax == IP_MAXPACKET. And over
> > > 64K
> > > isn't going to fit in 32 * 2K (mclbytes) clusters, etc and so
> > > forth.
> > >
> > > Anyhow, I think the attached patch will reduce if_hw_tsomax, so
> > > that
> > > the result should fit in 32 clusters and avoid EFBIG for this case,
> > > so it might be worth a try?
> > > (I still can't think of why the CSUM_TSO bit isn't set for the
> > > printf()
> > > case, but it seems TSO segments could generate EFBIG errors.)
> > >
> > > Maybe worth a try, rick
> > >
> > > > It's so old that I assume the TSO leak that he speaks of has been
> > > > patched, but perhaps not. More things to look into tomorrow.
> > > >
> > > >
> > > >
> > > >
> > > >
> > >
> > > _______________________________________________
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