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Date:      Sun, 7 Jul 2002 14:02:10 -0700
From:      Luigi Rizzo <rizzo@icir.org>
To:        Alan Cox <alc@FreeBSD.ORG>
Cc:        cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG
Subject:   Re: cvs commit: src/sys/vm vm_zeroidle.c
Message-ID:  <20020707140210.A64548@iguana.icir.org>
In-Reply-To: <200207071927.g67JRvwi019399@freefall.freebsd.org>; from alc@FreeBSD.ORG on Sun, Jul 07, 2002 at 12:27:57PM -0700
References:  <200207071927.g67JRvwi019399@freefall.freebsd.org>

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While you are on this file: there is a rather tricky bug
in the priority of the process.

It starts at RTP_PRIO_IDLE, but after the first tsleep
its priority gets raised to PPAUSE (which is much higher)
and never gets reset to the proper value.

The effect is that the process runs with very high priority,
and the only reason you don't notice (or maybe you do) is
that after a while the process does not have any more
pages to zero and voluntarily deschedules.

For a fix (rather trivial) have a look at

	sys/kern/kern_poll.c:poll_idle()

which does not have the nice property of descheduling
itself and so makes the bug quite evident.

	cheers
	luigi

On Sun, Jul 07, 2002 at 12:27:57PM -0700, Alan Cox wrote:
> alc         2002/07/07 12:27:57 PDT
> 
>   Modified files:
>     sys/vm               vm_zeroidle.c 
>   Log:
>    o Lock accesses to the free queue(s) in vm_page_zero_idle().
>   
>   Revision  Changes    Path
>   1.10      +4 -0      src/sys/vm/vm_zeroidle.c
> 
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