Re: [LSF/MM TOPIC][LSF/MM ATTEND] NAPI polling for block drivers

Johannes Thumshirn
2017-01-17T16:27:52Z

On Tue, Jan 17, 2017 at 06:15:43PM +0200, Sagi Grimberg wrote:
> Oh, and the current code that was tested can be found at:
>
> git://git.infradead.org/nvme.git nvme-irqpoll

Just for the record, all tests you've run are with the upper irq_poll_budget of
256 [1]?

We (Hannes and me) recently stumbed accross this when trying to poll for more
than 256 queue entries in the drivers we've been testing.

Did your system load reduce with irq polling? In theory it should but I have
seen increases with AHCI at least according to fio. IIRC Hannes saw decreases
with his SAS HBA tests, as expected.

[1] lib/irq_poll.c:13

Byte,
Johannes

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