On Wed, Feb 15, 2017 at 4:04 PM, Eric Dumazet <eric.duma...@gmail.com> wrote:
> On Wed, 2017-02-15 at 05:29 -0800, Eric Dumazet wrote:
>> mlx4_eq_int() is a hard irq handler.
>> How a tasklet could run in the middle of it ?
>> A tasklet is a softirq handler.
> Speaking of mlx4_eq_int() , 50% of cycles are spent on mb() (mfence)
> in eq_set_ci()

I wonder why you have so many interrupts ? don't you have some kind of
interrupt moderation ?
what test are you running that got your CPU so busy.

> I wonder why this very expensive mb() is required, right before exiting
> the interrupt handler.

to make sure the HW knows we handled Completions up to (ci) consumer
index. so it will generate next irq.

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