Date: Tue, 06 Sep 2005 09:39:42 -0700 From: Nate Lawson <nate@root.org> To: Robert Watson <rwatson@FreeBSD.org> Cc: Luigi Rizzo <rizzo@icir.org>, Gleb Smirnoff <glebius@FreeBSD.org>, cvs-all@FreeBSD.org, src-committers@FreeBSD.org, cvs-src@FreeBSD.org Subject: Re: cvs commit: src/sys/kern kern_poll.c Message-ID: <431DC64E.9010903@root.org> In-Reply-To: <20050906112608.N51625@fledge.watson.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>
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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. -- Nate
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