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

Jens Axboe
2017-01-11T16:15:29Z

On 01/11/2017 09:12 AM, hch@infradead.org wrote:
> On Wed, Jan 11, 2017 at 04:08:31PM +0000, Bart Van Assche wrote:
>> A typical Ethernet network adapter delays the generation of an interrupt
>> after it has received a packet. A typical block device or HBA does not delay
>> the generation of an interrupt that reports an I/O completion.
>
> NVMe allows for configurable interrupt coalescing, as do a few modern
> SCSI HBAs.

Unfortunately it's way too coarse on NVMe, with the timer being in 100
usec increments... I've had mixed success with the depth trigger.

--
Jens Axboe