From owner-freebsd-geom@FreeBSD.ORG  Fri Dec 10 15:59:15 2010
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To: Lev Serebryakov <lev@serebryakov.spb.ru>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Fri, 10 Dec 2010 18:33:22 +0300."
	<1136849868.20101210183322@serebryakov.spb.ru> 
Date: Fri, 10 Dec 2010 15:40:09 +0000
Message-ID: <56017.1291995609@critter.freebsd.dk>
Sender: phk@critter.freebsd.dk
Cc: freebsd-geom@freebsd.org
Subject: Re: One more question: is here any way to know is consumer busy or
	not? 
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In message <1136849868.20101210183322@serebryakov.spb.ru>, Lev Serebryakov writ
es:
>Hello, Freebsd-geom.
>
>  The  same  idea about pre-reading in case of providers with multiple
>  consumers   (BTW,   I   think  that terminology here is swapped):

The provider offers access to a disk(-like) device, which the consumer
can use.

>  looks  good  to  issue  pre-read only if target consumer is idle. Is
>  here  any  way  to  determine  that? 

you can look at the nstart and nend elements of the g_consumer structure
to tell how many outstanding requests there are on that consumer.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.