cvs commit: src/sys/kern kern_poll.c

[Scott Long]

Nate Lawson wrote:
> Robert Watson wrote:
> 
>>
>> On Tue, 6 Sep 2005, Luigi Rizzo wrote:
>>
>>> On Tue, Sep 06, 2005 at 10:18:28AM +0400, Gleb Smirnoff wrote:
>>>
>>>>   Luigi,
>>>
>>>
>>> ...
>>>
>>>> The idlepoll thread is single.
>>>
>>>
>>>
>>> ok this is very good. Re. netisr vs idlepoll, perhaps a way could be 
>>> to bump the idlepoll priority very high upon a net soft interrupt, 
>>> and drop it down to its normal value once done with the netisr cycle. 
>>> so we don't have to arbitrate among the two.
>>
>>
>> Also, if we gradually move to a polling model that handles polling for 
>> non-network devices, it would result in a rather mixed model.  One of 
>> the challenges of moving to a mixed polling model (one that supports 
>> non-network devices) is that network devices have a fairly well 
>> understood currency for work: processing of packets.  Other devices 
>> may have less well understood, or at least not easily comparable, 
>> workloads...
> 
> 
> For the case of storage, you actually have a better model since all 
> transactions are initiated from the host (as opposed to packet 
> arrivals).  This gives an easy metric for a dynamic polling threshold -- 
> if you have a deep queue of outstanding requests and one completes, you 
> should poll a little more than normal.
> 

Except for target mode.

Scott