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

Hannes Reinecke
2017-01-11T16:45:08Z

On 01/11/2017 05:26 PM, Bart Van Assche wrote:
> 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.
>
Guess what we'll be doing in the next few days ...

Cheers,

Hannes
--
Dr. Hannes Reinecke zSeries & Storage
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