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Date: Wed, 4 Oct 2017 00:15:15 +0200
From: Alex Kozlov <ak@FreeBSD.org>
To: Allan Jude <allanjude@freebsd.org>,
 "Michael W. Lucas" <mwlucas@michaelwlucas.com>
Cc: hackers@freebsd.org
Subject: Re: vmstat's w column
Message-ID: <20171003221514.GA74686@ravenloft.kiev.ua>
References: <20171003202150.GA42540@mail.michaelwlucas.com>
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On Tue, Oct 03, 2017 at 04:31:17PM -0400, Allan Jude wrote:
> On 10/03/2017 16:21, Michael W. Lucas wrote:
> > Hi,
> > 
> > (This query brought to you courtesy of tech reviews on my new freeBSD
> > book.)
> > 
> > On my -current box, vmstat(8) says:
> > 
> >      procs   Information about the numbers of processes in various states.
> > 
> >              r       in run queue
> >              b       blocked for resources (i/o, paging, etc.)
> >              w       runnable or short sleeper (< 20 secs) but swapped
> > 
> > I've had a couple people report to me that they have w entries even
> > when only a few kilobytes are swapped out.
> > 
> > Is the man page wrong? Or should I tell them to report that output as
> > a bug?
> > 
> I wonder if the explanation needs a comma.
> It could be read as: running, or [short sleeper that is swapped out]
This field corresponds to vmtotal.t_sw counter (see vm.vmtotal sysctl).
Its increases in two cases: thread is swapped out (TDI_SWAPPED state)
or thread is ready to run, but not in the run queue.
The short sleeper part was removed in r103216 (see kg->kg_slptime < maxslp line): 
https://svnweb.freebsd.org/base/head/sys/vm/vm_meter.c?r1=99072&r2=103216


-- 
Alex