Processes are incorrectly marked as swapped out
John Baldwin
jhb at freebsd.org
Tue Jan 28 17:35:23 UTC 2014
On Thursday, January 23, 2014 8:02:29 am Ronald Klop wrote:
> On Thu, 23 Jan 2014 13:19:36 +0100, Dmitry Sivachenko
> <trtrmitya at gmail.com> wrote:
>
> > Hello!
> >
> > After upgrade from stable/9 to stable/10 I see the following regression.
> > Some processes are marked as swapped out in top(1) output:
> >
> > 1436 root 1 43 0 16524K 0K nanslp 14 1:14 0.00%
> > <cron>
> > 1381 smmsp 1 20 0 23988K 0K pause 18 0:04 0.00%
> > <sendma
> > 99348 mitya 1 21 0 23492K 0K pause 16 0:00 0.00%
> > <csh>
> >
> > ps(1) also shows them as swapped out (W as second character in state
> > field):
> > 1381 - IWs 0:00.00 sendmail: Queue runner at 00:30:00 for
> > /var/spool/clie
> > 1436 - IWs 0:00.00 /usr/sbin/cron -s
> > 80231 - IWs 0:00.00 /usr/local/sbin/collectdmon -c
> > /usr/local/sbin/coll
> > 99348 1 IWs 0:00.00 -csh (csh)
> >
> > Though swapinfo reports that zero swap is used and even if I turn swap
> > completely off (swapoff -a)
> > the output of both top(1) and ps(1) does not change: these processes are
> > still marked as swapped out.
>
> The code of an application can get removed from memory, because there
> still is an image of it in the executable on disk. It can be 'swapped' in
> by reading the executable again. The program is memory mapped (mmap).
> See VN PAGER vs SWAP PAGER in 'systat -vm'.
However, a swapped out process always uses swap (for kernel stacks), so this
seems like a real bug.
--
John Baldwin
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