RFC: use EM_LEGACY_IRQ in if_lem.c ?

Jack Vogel jfvogel at gmail.com
Tue Jul 24 22:07:53 UTC 2012


Interesting, lem is all the non-pcie hardware, and if you see better
performance
out of the LEGACY path then I'm OK with changing the default.

Jack


On Tue, Jul 24, 2012 at 1:20 PM, Luigi Rizzo <rizzo at iet.unipi.it> wrote:

> if_lem.c ("lem", one of the e1000 drivers) has 2 possible interrupt modes:
> EM_LEGACY_IRQ uses the standard dispatch mechanism, whereas
> FAST_INTR has a custom handler that signals a taskqueue to do the job.
>
> I have no idea which actual hardware uses it (all of my Intel 1G
> cards use either "em" or "igb"), but "lem" is the driver used in
> qemu, and there the EM_LEGACY_IRQ gives approx 10% higher packet
> rates than the other.
>
> Any objections if i change the default to EM_LEGACY_IRQ ?
>
>         cheers
>         luigi
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