ixgbe rx & tx locks

[Jack Vogel]

Hmmm, this is odd, because the interrupt vector is not being re-enabled
unless
you are not scheduling the task, and when you are the interrupt isn't
enabled til
the end.... Something funny going on.

You could get contention due to mq_start however, you sure about where its
coming from?

Jack



On Mon, Aug 13, 2012 at 2:15 PM, Vijay Singh <vijju.singh at gmail.com> wrote:

> Folks, I've been looking into lock contention on the ixgbe rx & tx locks.
>
> I have collected this data:
>
> debug.lock.prof.stats:
>      max  wait_max       total  wait_total       count    avg wait_avg
> cnt_hold cnt_lock name
>      263       304     1329357      858873      322010      4      2
> 0  45210 sys/dev/ixgbe/ixgbe.c:1349 (sleep mutex:e2a:tx(0))
>      415       189    14314889       62933      739895     19      0
> 0  13694 sys/dev/ixgbe/ixgbe.c:1445 (sleep mutex:e2a:tx(0))
>
> So the lock contention is coming from lock acquisitions in
> ixgbe_handle_que() and ixgbe_msix_que().
>
> I am unable to understand why, since I would not expect the deferred
> task to execute in parallel with the msix interrupt handler.
>
> rx is similar:
>
> debug.lock.prof.stats:
>      max  wait_max       total  wait_total       count    avg wait_avg
> cnt_hold cnt_lock name
>       88       893      672058      269855      821847      0      0
> 0    753 sys/dev/ixgbe/ixgbe.c:4211 (sleep mutex:e6b:rx(0))
>      893        25     3994289        1937     1093238      3      0
> 0    561 sys/dev/ixgbe/ixgbe.c:4276 (sleep mutex:e6b:rx(0))
>
> Any thoughts?
>
> -vijay
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