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

Bart Van Assche
2017-01-11T16:26:40Z

On Wed, 2017-01-11 at 17:22 +0100, Hannes Reinecke wrote:
> On 01/11/2017 05:12 PM, 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.
>
> Essentially every modern SCSI HBA does interrupt coalescing; otherwise
> the queuing interface won't work efficiently.

Hello Hannes,

The first e-mail in this e-mail thread referred to measurements against a
block device for which interrupt coalescing was not enabled. I think that
the measurements have to be repeated against a block device for which
interrupt coalescing is enabled.

Bart.