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Date:      Tue, 06 Sep 2005 11:16:43 -0600
From:      Scott Long <scottl@samsco.org>
To:        Nate Lawson <nate@root.org>
Cc:        src-committers@FreeBSD.org, Luigi Rizzo <rizzo@icir.org>, cvs-all@FreeBSD.org, Gleb Smirnoff <glebius@FreeBSD.org>, Robert Watson <rwatson@FreeBSD.org>, cvs-src@FreeBSD.org
Subject:   Re: cvs commit: src/sys/kern kern_poll.c
Message-ID:  <431DCEFB.9030005@samsco.org>
In-Reply-To: <431DC64E.9010903@root.org>
References:  <200509051602.j85G2Bpo090258@repoman.freebsd.org> <20050905094341.A23343@xorpc.icir.org> <20050905180050.GB41863@cell.sick.ru> <20050905141451.A27290@xorpc.icir.org> <20050906061828.GQ41863@cell.sick.ru> <20050906012755.B34182@xorpc.icir.org> <20050906112608.N51625@fledge.watson.org> <431DC64E.9010903@root.org>

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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



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