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

[Johannes Thumshirn]

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

-- 
Johannes Thumshirn                                          Storage
jthumshirn at suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850