Date: Tue, 25 Sep 2012 13:19:01 -0700 From: Vijay Singh <vijju.singh@gmail.com> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-net@freebsd.org, Jack Vogel <jfvogel@gmail.com> Subject: Re: ixgbe rx & tx locks Message-ID: <CALCNsJQ740ceDzpd5n7QAALn-uJ-GdWxPTkQJuMJUMTUGJjOUg@mail.gmail.com> In-Reply-To: <201208170941.54482.jhb@freebsd.org> References: <CALCNsJSSQSWV7vNVR-Sn8CPDKbUBBLpSH0b-HYMJo3SXvkOY=w@mail.gmail.com> <201208161736.47250.jhb@freebsd.org> <CAFOYbc=bXv_V4egO94ftkTFoLQ2uM50Sw3X5kgYoyKQcd0s31A@mail.gmail.com> <201208170941.54482.jhb@freebsd.org>
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> Vijay, can you test this to see if it helps with your test case?
>
>> Jack
John, apologies for the delay. I have some data to share now.
With your patch, the transmit side lock contention is all gone.
However I still see receive side contention. I have MSI/X enabled,
with one hw queue per-port.
debug.lock.prof.stats:
lock held_at
contested_from instances
e1b:rx(0) ( sys/dev/ixgbe/ixgbe.c:4314) (
sys/dev/ixgbe/ixgbe.c:4249) 6814
e2b:rx(0) ( sys/dev/ixgbe/ixgbe.c:4314) (
sys/dev/ixgbe/ixgbe.c:4249) 6962
These are from:
4297 static bool
4298 ixgbe_rxeof(struct ix_queue *que, int count)
4299 {
.....
4314 IXGBE_RX_LOCK(rxr);
and
4220 static __inline void
4221 ixgbe_rx_input(struct rx_ring *rxr, struct ifnet *ifp, struct
mbuf *m, u32 ptype)
4222 {
....
4247 IXGBE_RX_UNLOCK(rxr);
4248 (*ifp->if_input)(ifp, m);
4249 IXGBE_RX_LOCK(rxr);
So it seems like the interrupt handler is still contending with a
taskqueue handler on the receive side.
-vijay
PS: The interface names are custom.
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