Date: Fri, 17 Aug 2012 09:41:54 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-net@freebsd.org Cc: Jack Vogel <jfvogel@gmail.com>, Vijay Singh <vijju.singh@gmail.com> Subject: Re: ixgbe rx & tx locks Message-ID: <201208170941.54482.jhb@freebsd.org> In-Reply-To: <CAFOYbc=bXv_V4egO94ftkTFoLQ2uM50Sw3X5kgYoyKQcd0s31A@mail.gmail.com> References: <CALCNsJSSQSWV7vNVR-Sn8CPDKbUBBLpSH0b-HYMJo3SXvkOY=w@mail.gmail.com> <201208161736.47250.jhb@freebsd.org> <CAFOYbc=bXv_V4egO94ftkTFoLQ2uM50Sw3X5kgYoyKQcd0s31A@mail.gmail.com>
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On Thursday, August 16, 2012 5:40:35 pm Jack Vogel wrote: > Thanks John, am seeing this, just busy on another matter, will get to it > asap. Vijay, can you test this to see if it helps with your test case? > Jack > > > On Thu, Aug 16, 2012 at 2:36 PM, John Baldwin <jhb@freebsd.org> wrote: > > > On Thursday, August 16, 2012 8:35:53 am John Baldwin wrote: > > > On Monday, August 13, 2012 6:17:53 pm Jack Vogel wrote: > > > > After looking at the code again I think this is just what's happening, > > > > mq_start > > > > will schedule the task when it can't get the lock (due to the interrupt > > > > already > > > > holding it presumeably), so you get the tasklet code in contention > > with the > > > > interrupt. > > > > > > > > Anyone with a clever notion of how to do things better? > > > > > > Are you queueing a task that does both RX and TX? That was a bug I fixed > > > in igb that caused out-of-order packet processing for RX with igb. igb > > > uses a smaller task for when it's start routine fails that only tries to > > > restart transmission but doesn't do fullblown interrupt handling. > > > > > > Here's a possible patch (compiles, not run-tested) to implement this for > > > ixgbe: > > > > > > http://www.FreeBSD.org/~jhb/patches/ixgbe_txq_task.patch > > > > Actually, it looks like recent changes to the watchdog handling have > > reintroduced a variant of this bug. They schedule the full RX/TX task > > to run anytime the timer fires and there are pending TX completions > > that are in progress. This seems a bit odd as in the normal case you > > will get a TX completion interrupt once there is something to do. OTOH, > > it adds another instance of duplicate RX processing which is much worse > > than what this is trying to fix. I've updated this patch to disable > > that bit of the watchdog handler in both igb and ixgbe: > > > > http://www.FreeBSD.org/~jhb/patches/ixgbe_txq_task2.patch > > > > -- > > John Baldwin > > > _______________________________________________ > 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" > -- John Baldwin
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