From owner-freebsd-hackers  Sun Jul 14  9:48: 0 2002
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Date: Sun, 14 Jul 2002 09:47:56 -0700
From: Luigi Rizzo <rizzo@icir.org>
To: David Miller <dmiller@sparks.net>
Cc: hackers@FreeBSD.ORG
Subject: Re: setsockopt() weirdness
Message-ID: <20020714094756.G74633@iguana.icir.org>
References: <20020714085832.C74633@iguana.icir.org> <Pine.BSF.4.21.0207141241480.15972-100000@search.sparks.net>
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In-Reply-To: <Pine.BSF.4.21.0207141241480.15972-100000@search.sparks.net>; from dmiller@sparks.net on Sun, Jul 14, 2002 at 12:43:51PM -0400
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On Sun, Jul 14, 2002 at 12:43:51PM -0400, David Miller wrote:
> On Sun, 14 Jul 2002, Luigi Rizzo wrote:
> 
> > On Sun, Jul 14, 2002 at 11:49:46AM -0400, David Miller wrote:
> > ...
> > > HZ is set to 5000; the machine is intended to process several tens of
> > > thousands of very small packets per second, and interrupt processing was a
> > > big problem.
> > 
> > why don't you use "options DEVICE_POLLING" then :)
> 
> I am.  Perhaps I understood wrong, but I thought that HZ controlled the
> maximum latency when polling?  

oh yes, but HZ=5000 sounds a bit on the high side... do you really
need a max latency of 200us ?? Plus, you still poll in the idle loop,
so unless the box is overloaded, your average latency will still be
shorted than 1/HZ.

(all of this is of course irrelevant for the original subject:)

	cheers
	luigi

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