Date: Thu, 16 Aug 2012 14:40:35 -0700 From: Jack Vogel <jfvogel@gmail.com> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-net@freebsd.org, Vijay Singh <vijju.singh@gmail.com> Subject: Re: ixgbe rx & tx locks Message-ID: <CAFOYbc=bXv_V4egO94ftkTFoLQ2uM50Sw3X5kgYoyKQcd0s31A@mail.gmail.com> In-Reply-To: <201208161736.47250.jhb@freebsd.org> References: <CALCNsJSSQSWV7vNVR-Sn8CPDKbUBBLpSH0b-HYMJo3SXvkOY=w@mail.gmail.com> <CAFOYbcm7nzKA3ZR9F8fVLY2Q4839FDOC61PNjwNpQy1WBxL1Hw@mail.gmail.com> <201208160835.53303.jhb@freebsd.org> <201208161736.47250.jhb@freebsd.org>
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Thanks John, am seeing this, just busy on another matter, will get to it asap. 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 >
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